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This paper presents the design of a low-profile circularly polarized dual-beam holographic antenna. Firstly, by employing a novel outer square inner circular (OSIC) structure as the basic unit of the hologram pattern, better performance is achieved for lowprofile dielectric substrate holographic antennas. Secondly, a method of four-zone phase co-modulation is used to derive the impedance modulation formula of the hologram pattern. This formula was employed to model and generate a circularly polarized dual-beam holographic antenna, and the feasibility of theoretical analysis is verified through simulation and measurement. The antenna operates within the frequency range of 10.23 GHz to 16.59 GHz, with maximum gains of 16 dBi and 15.8 dBi for dual beams, respectively. The results indicate that this design method can realize circularly polarized dual-beam holographic antennas and provide some reference for satellite communication applications. [ABSTRACT FROM AUTHOR]

This study introduces a metasurface-based low-profile circularly polarized (CP) antenna with double-wide beam for global navigation satellite systems (GNSSs), which covers primarily BDS-2 B1 band and BDS-3 B1 band. At first, a T-slot structure achieving a compact design is presented to effectively miniaturize the antenna. Except that, a gear-type parasitic ring and eight parasitic microstrip lines are proposed to broaden both the half power beamwidth (HPBW) and axial ratio beamwidth (ARBW) of the antenna. Furthermore, a metasurface unit featuring double "WIFI" logo structure is introduced. This unit is expanded into a 7 * 7 metasurface loaded under the antenna, significantly improving its radiation characteristics. After experimentation, the proposed antenna achieves notable results: 121° HPBW and 214° 3 dB-ARBW at 1.561 GHz and 121° HPBW and 236° 3 dB-ARBW at 1.575 GHz. Additionally, it demonstrates more than 3.52 dBic gain across the whole frequency band, whose simulation and test results are in agreement. These results show that the antenna can be used for various satellite communication systems necessitating CP antennas with wide ARBW and HPBW. [ABSTRACT FROM AUTHOR]

In this paper, a new UWB antenna for the Internet of Things (IoT) based on a left-handed structure is designed. The antenna utilizes a microstrip feeder and consists of a new complementary split ring resonator (CSRR) equipped with a three-stage double rectangular electromagnetic resonator (RER) to form the main radiator with left-handed characteristics. It also includes a double L-shaped parasitic patch and a slotted ground. The dimensions of the antenna are 0.42 × 0.42 × 0.013λ0³. It covers the frequency band of 1.70-3.34 GHz (65.1%), which includes the communication frequency bands used by IoT antennas. The antenna exhibits good directional patterns within this frequency band. The measured peak gain is 5.49 dBi, making it suitable for applications in Wi-Fi, Bluetooth, Zigbee technology, and other fields. [ABSTRACT FROM AUTHOR]

The campaign life of a blast furnace is largely limited by the erosion state of its hearth section. Therefore, the study of hearth erosion is important for blast furnace ironmaking. In this study, the hearth erosion of the WISCO No. 1 blast furnace was investigated in combination with the numerical analysis of the iron flow and heat transfer in the hearth. The distributions of the wall shear stress and the temperature in the hearth were simulated and the hearth sections with high erosion risk were discussed. The hearth lining with higher shear stress is generally located near the taphole region and the 1423 K isotherm is totally located inside the hearth lining structure, with a deeper position in the central part of the hearth bottom. Based on the measurement data from the hearth damage investigation, the erosion state of the hearth bottom and the lower part of the hearth sidewall is more serious. The erosion line at the hearth bottom showed a typical “pot-bottom” shaped contour and for the hearth corner section, the average erosion depth was about 1/3 of the total wall thickness. The empirical expressions between the hearth erosion depth and the wall shear stress and the temperature were established. Moreover, the effects of key iron tapping factors on the wall shear stress and the effect of the hearth’s refractory structure on the heat transfer in the hearth are respectively discussed, aiming to provide more suggestions for hearth protection.

Surface damages caused by markings, like laser marking and mechanical marking are detrimental to the fatigue performance of the components. To improve the fatigue performance of laser marked or mechanical marked Ti-6Al-4V alloy, ultrasonic surface rolling process (USRP) was performed on Ti-6Al-4V alloy prior to marking. The results showed that laser marking induced a porous and loose oxidized layer which severely decreased the fatigue performance of the substrate. And the mechanical marking slightly decreased the fatigue performance of the substrate due to the local stress concentration at the bottom of the pits. After USRP pretreatment, the detrimental effect of laser marking on the fatigue performance of the substrate was eliminated while the fatigue performance of mechanical marking sample was significantly improved by a factor of 3. That was because the USRP-induced residual compressive stress suppressed the crack early propagation. Key words: Titanium alloy; Fatigue; Ultrasonic surface rolling process; Surface damage; Residual compressive stress; Laser marking, Mechanical marking