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306 results on '"Huang, Kama"'

17. Experimental Investigation on Electrical Conductivity Variation of Carnosine and Zinc Chloride Aqueous Solutions under Microwave Irradiation

Author

Zhao, Chenxi, Ma, Yun, Hou, Desheng, Wang, Lin, Hong, Tao, Tang, Zhengming, Huang, Kama, and Gou, Dezhi

Abstract

The mechanism of biological effects of environmental electromagnetic radiation is still not completely clear. The chelation of biological small molecule peptides with metal ions plays a very important role in human metabolism. In this paper, a special experimental system was designed to measure the conductivity of carnosine and zinc chloride mixed aqueous solutions under different concentration ratios, microwave powers, and temperatures. The experimental results show that, first, different concentration ratios can alter the conductivity change rate of the mixed aqueous solution. The conductivity of the solution always increases under microwave irradiation at a concentration ratio of 1:1. However, the conductivity is reduced by −0.04% with a 1:5 concentration ratio and 6 W microwave power at 10 °C. Second, temperature can alter the conductivity change rate of the aqueous mixture. The higher the temperature, the smaller the conductivity change rate. Third, different microwave powers can alter the conductivity change rate of the mixed aqueous solution. In general, the conductivity change rate increases with an increase in microwave power. Experimentally observed reduction of the conductivity change rate in carnosine and zinc chloride aqueous solution under low microwave power and low temperature indicates that microwaves do affect the chelation of carnosine with zinc chloride. This work provides a new perspective for the mechanism of explanation of microwave biological effects.

Published
2024
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18. A Polarization-Insensitive Rectifying Surface for 2.4 GHz WLAN Band RF Energy Harvesting

Author

Wang, Huai-Yu, Cheng, Fei, Yang, Yang, Chen, Xing, Wu, Li, Gu, Chao, and Huang, Kama

Abstract

This article introduces a polarization-insensitive rectifying surface for 2.4 GHz WLAN band RF energy harvesting. The unit cell of the rectifying surface is formed by combining an interdigital structure with a square ring structure, optimized for high RF harvest efficiency over a wide band. For optimal performance, our design employs a direct matching of the Schottky diodes to the rectifying surface, minimizing signal loss and enhancing rectification effectiveness. To demonstrate the concept, a $4\times 4$ element rectifying surface array was fabricated and measured, yielding a total efficiency of 21% at an incident power density of $2.62~\mu $ W/cm2. The measured total efficiency remains higher than 18.9% over the 2.4–2.57 GHz range, covering the 2.4 GHz WLAN band. Furthermore, the total efficiency remains constant despite variations in the polarization angle of the incident wave. Our design demonstrates a highly efficient rectifying surface for harvesting low-power energy within the 2.4 GHz WLAN band, offering a promising solution for powering wireless devices.

Published
2024
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25. A Low Profile High Gain Ultra Lightweight Circularly Polarized Annular Ring Slot Antenna for Airborne and Airship Applications

Author

Nouman Rasool, Huang Kama, Muhammad Abdul Basit, and Mujeeb Abdullah

Subjects
CPARSA, circular polarization, microstrip-fed slot, wideband, slot antenna, airborne, Electrical engineering. Electronics. Nuclear engineering, TK1-9971
Abstract

In this paper a low profile circularly polarized annular ring slot antenna (CPARSA) with high gain is presented. An inverted U-shaped meandered slot is cut at the inner patch of annular ring to obtain the circularly polarized (CP) radiation. This annular slot loaded ground plane on a substrate thickness of 0.5 mm results in a very low profile (0.009λ0) antenna in term of free space wavelength at its center operating frequency. The largest side lengths of octagonal shaped antenna are 0.89λ0 × 0.89λ0 according to its center frequency. Measured impedance bandwidth of 23.54% from 5.4 GHz - 7.0 GHz (for |S11| ≤ -10 dB) and AR bandwidth (AR

Published
2019
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26. CPW-fed circularly-polarized antenna array with high front-to-back ratio and low-profile

Author

Liu Yilin and Huang Kama

Subjects
low-profile antenna, coplanar waveguide, cpw–slotline transition, circular polarization, sequential feeding, 41.20.jb, 84.40.ba, Physics, QC1-999
Abstract

A novel design of a coplanar waveguide (CPW) feed antenna array with circular polarization (CP) and a high front-to-back ratio is described. The proposed CP array is achieved by using a compact CPW–slotline transition network etched in the ground plane. The measured results show that this kind of feeding method can improve the impedance bandwidth, as well as the axial ratio bandwidth of the CP antenna array and provide adequate gain. The proposed array can achieve a 6.08% impedance bandwidth and a 4.10% CP bandwidth. Details of the antenna design and experimental results are presented and discussed.

Published
2018
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29. Mitigating Thermal Focusing in Microwave Heating of Cylindrical Loads by Resonant Rings.

Author

Yang, Fengming, Yan, Xueting, Zhu, Huacheng, Yang, Yang, and Huang, Kama

Subjects
HEATING load, MICROWAVE heating, MICROWAVES, TEMPERATURE distribution
Abstract

Cylindrical loads are commonly found in microwave heating. However, cylindrical loads tend to have a thermal focus, leading to uneven microwave heating. In this paper, a novel microwave heating method was proposed by employing resonant rings to mitigate the thermal focus of cylindrical loads. Firstly, a multiphysics simulation model for microwave heating of a cylindrical tube is established, and the influence of the resonant ring around the cylindrical tube on the temperature distribution of load was analyzed. Subsequently, microwave heating experiments of agar gels with and without resonant rings were carried out. In agreement with the simulation results, the use of resonant rings reduces the coefficient of temperature variation (COV) from 1.064 to 0.793. In addition, the parameters affecting the heating uniformity of the cylindrical tube were discussed through simulations. [ABSTRACT FROM AUTHOR]

Published
2023
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46. Influence of Microwave Frequency and Gas Humidity on the In-Vitro Blood Coagulation in Cold Atmospheric Pressure Plasma

Author

Li Wu, Huang Kama, and Jie Yu

Subjects
Chromatography, Blood clotting, Chemistry, Process Chemistry and Technology, Chemical technology, Thermal effect, Humidity, Bioengineering, Plasma treatment, Atmospheric-pressure plasma, Plasma, Microwave frequency, TP1-1185, gas humidity, cold atmospheric plasma, blood coagulation, Chemical Engineering (miscellaneous), Coagulation (water treatment), microwave frequency effect, QD1-999
Abstract

In this article, the effects of microwave frequency (2450 MHz and 5800 MHz) and gas humidity (1%, 2%, 3%, 4%, 6% and 8%) on in vitro blood coagulation with cold atmospheric pressure plasma (CAPP) were investigated. The generation of reactive oxygen species (ROS, OH, O) was measured by optical emission spectra. The exposure temperature on blood droplets under treatment was below 55 °C in all cases, to avoid the thermal effect of plasma on the blood clotting. Investigations showed that, with the increase of frequency, the doses of ROS increased, the blood sample presented a more serious collapse and its surface became drier. The humidity of ionized gas can also accelerate the generation of ROS and the process of blood clotting. Our results propose a method to accelerate in vitro blood coagulation in CAPP by adjusting microwave frequency and gas humidity, and suggest a clinical benefit for plasma treatment as a coagulation device in surgery.

Published
2021
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