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Design of a C-band Reflector Antenna with a Splash-plate Feed
Jie Lian,Kyung Park,Andrii Gorshkov,Bierng-Chearl Ahn 한국정보기술학회 2019 한국정보기술학회논문지 Vol.17 No.12
This paper presents an optimum design of a C-band reflector antenna fed by a splash-plate feed. The designed antenna consists of a parabolic reflector with an apex plate and a splash-plate feed integrated with a circular waveguide. The splash plate has a central cone for reflection reduction and a dielectric support structure for integration with a circular waveguide. An apex plate is placed at the center of the parabolic reflector for sidelobe reduction. An optimum antenna design has been obtained by suitable choice of reflector illumination angle, diameter and location of the splash plate, the shape and size of an apex plate, and by good impedance matching of the splash plate feed. The designed antenna operates at 4.8-5.7GHz with reflection coefficient of less than -10dB. At the frequency of 5.1GHz, the antenna has 30.8 dBi gain (67.3% aperture efficiency), 4.9° E-plane beamwidth, 4.7° H-plane beamwidth, -21.0dB E-plane sidelobe, -20.8dB H-plane sidelobe, and maximum cross-polarization gain of -5dBi.
Konjac Glucomannan Derived Carbon Aerogels for Multifunctional Applications
Jie Lian,Jiwei Li,Liang Wang,Ru Cheng,Xiuquan Tian,Xue Li,Jian Zhou,Tao Duan,Wenkun Zhu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.10
Environmental and energy issues have always been a hot topic of global research. Oil leakage has caused great damage to the environment, affecting a wide area and it is difficult to clean up. In most cases, carbon-based adsorbents are typically utilized to remove oil spills because of their economic benefits and high adsorbent efficiency. At the same time, its excellent material properties can also be used for the preparation of supercapacitors. In this paper, the carbon aerogels were prepared by the one-step method. The prepared materials endowed a 3D network structure with a huge number of micropores and mesoporous, and the material is light-weight, stable, hydrophobic and has affinity for oil (17.02 g/g) to the KGM carbon aerogel. Through the physicchemical characterization, the KGM carbon aerogel shows specific surface area is 689m2/g, high water contact angle (136.64°) and excellent reusability (more than 15 cycle times). In addition, we also discussed the electrochemical properties of the material and obtained the specific electrical capacity of 139 F/g under the condition of 1 A/g.
Sliding Mode Control of Uncertain Switched Delay Systems via Hysteresis Switching Strategy
Jie Lian,Jun Zhao 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.6
This paper investigates the robust sliding mode control (SMC) problem for a class of uncertain switch-ed systems with time-varying delay. The sliding surface is constructed such that the sliding motion is completely invariant to all admissible uncertainties. For the case of the known delay-derivative upper bound, by using the multiple Lyapunov functions method, the Hysteresis switching law dependent on the state and the previous value of switching signal are designed to stabilize the sliding motion and avoid the chattering. Variable structure controllers are developed to drive the state of switched systems to reach the sliding surface in finite time and remain on it thereafter. For the case of the unknown delay-derivative upper bound, based on the single Lyapunov function method, the conditions of stabilization are obtained. Finally, a numerical example is given to illustrate the effectiveness of the proposed methods.
Value distribution of difference operator on meromorphic functions
Jie Ding,Lian-Zhong Yang 대한수학회 2014 대한수학회보 Vol.51 No.5
In this paper, we investigate the value distribution of the difference operator on meromorphic functions, and obtain a difference analogue of a theorem of Hayman on meromorphic functions.
Investigation of random fatigue life prediction based on artificial neural network
Jie Xu,Chongyang Liu,Xingzhi Huang,Yaolei Zhang,Haibo Zhou,Hehuan Lian 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.3
Time domain method and frequency domain method are commonly used in the current fatigue life calculation theory. The time domain method has complicated procedures and needs a large amount of calculation, while the frequency domain method has poor applicability to different materials and different spectrum, and improper selection of spectrum model will lead to large errors. Considering that artificial neural network has strong ability of nonlinear mapping and generalization, this paper applied this technique to random fatigue life prediction, and the effect of average stress was taken into account, thereby achieving more accurate prediction result of random fatigue life.
Preparation and properties of ZrB2-YAG-Al2O3 ceramics
Jie-Guang Song,Gang-Chang Ji,Shi-Bin Li,Yang-Liang Li,Da-Ming Du,Lian-Meng Zhang,Yin-Yan Ju 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.4
ZrB2, YAG and Al2O3 are widely applied because of some excellent properties, but ZrB2 is easily oxidized in high-temperature air. To achieve better properties in ZrB2 ceramics, high-density ZrB2-YAG-Al2O3 ceramics were prepared. Below 1000℃, the shrinkage of ZrB2-YAG-Al2O3 ceramics is less than that of ZrB2-YAG ceramics. From 1000℃ to 1600℃, the second largest shrinkage occurs. Above 1600℃, the shrinkage of ZrB2-YAG-Al2O3 ceramics is more than that of ZrB2-YAG ceramics. The fracture toughness of sintered ceramics from coated raw materials is higher than that of sintered ceramics with mixed raw materials with the same phases and phase content, the fracture toughness of ZrB2-YAG-Al2O3 ceramics is higher than that of ZrB2-YAG ceramics with the same raw materials. The weight gain of all types of ceramics is increased with all increase in the oxidation temperature, the weight gain of ceramics is reduced with all increase in the YAG-Al2O3 content and Al2O3 proportion, especially above 1500℃. ZrB2, YAG and Al2O3 are widely applied because of some excellent properties, but ZrB2 is easily oxidized in high-temperature air. To achieve better properties in ZrB2 ceramics, high-density ZrB2-YAG-Al2O3 ceramics were prepared. Below 1000℃, the shrinkage of ZrB2-YAG-Al2O3 ceramics is less than that of ZrB2-YAG ceramics. From 1000℃ to 1600℃, the second largest shrinkage occurs. Above 1600℃, the shrinkage of ZrB2-YAG-Al2O3 ceramics is more than that of ZrB2-YAG ceramics. The fracture toughness of sintered ceramics from coated raw materials is higher than that of sintered ceramics with mixed raw materials with the same phases and phase content, the fracture toughness of ZrB2-YAG-Al2O3 ceramics is higher than that of ZrB2-YAG ceramics with the same raw materials. The weight gain of all types of ceramics is increased with all increase in the oxidation temperature, the weight gain of ceramics is reduced with all increase in the YAG-Al2O3 content and Al2O3 proportion, especially above 1500℃.