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Search Results: 1 - 10 of 127272 matches for " Pengcheng Zhao;Cheng Liao;Wenbin Lin;Ju Feng "
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Effects of Microwave Frequency on Electron Energy Distribution Function and Air Breakdown Using the Fluid Model
Pengcheng Zhao;Cheng Liao;Wenbin Lin;Ju Feng
PIER M , 2012, DOI: 10.2528/PIERM12101201
Abstract: The non-equilibrium electron energy distribution function (EEDF) obtained via solving the Boltzmann equation is introduced into the fluid model, and the effects of the microwave frequency on the EEDF and air breakdown are investigated. Numerical simulations show that the breakdown threshold of the fluid model with the non-equilibrium EEDF agrees well with that of the reported experiments. The microwave frequency plays an important role on the shape of the non-equilibrium EEDF at low pressures. The breakdown time at the low pressures predicted by the Maxwellian EEDF is shorter than that from the non-equilibrium EEDF in low-frequency oscillating fields, while matches the latter in high-frequency oscillating fields.
Analysis of Reflection Properties of High Power Microwave Propagation in Mixture-Atmosphere  [PDF]
Tao Tang, Cheng Liao, Qingmin Gao, Pengcheng Zhao
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2010, DOI: 10.4236/jemaa.2010.29070
Abstract: A simple theoretical modeling is made to describe the reflection features of the high power microwave (HPM) in the mixture-atmosphere. The time-space dependent mixture-atmosphere is generated by ionization of the neutral molecules in atmosphere. Reflection will occur when HPM propagates in such mixture-atmosphere. The reflection characteristic of the HPM propagation in the mixture-atmosphere is investigated by FDTD numerical experiments in inhomogeneous medium, the influence on the reflection for different HPM parameters is concluded. An additional stability conditions for the FDTD difference scheme of the HPM mixture-atmosphere propagation model are presented.
Characteristics Analysis of Repetition Frequency High-Power Microwave Pulses in Atmosphere
Tao Tang;Cheng Liao;Wenbin Lin
PIER M , 2010, DOI: 10.2528/PIERM10092010
Abstract: A semi-analytical model for the propagation of the repetition frequency high power microwave (HPM) pulses is established. The effects of different parameters of the repetition frequency HPM pulses on air breakdown are analyzed. A critical repetition frequency for the HPM pulse is presented under which the electron density does not exceed that of the air breakdown when the individual pulse arrives. The prediction for the critical repetition frequency and the threshold of the air breakdown due to the repetition frequency HPM pulses is demonstrated with several numerical simulations.
Time-Delay-Based Multi-Target Detection and Power Delivering
Xuan-Ming Zhong;Cheng Liao;Wenbin Lin
PIER M , 2011, DOI: 10.2528/PIERM11042502
Abstract: The paper presents an approach to locate and concentrate electromagnetic energy on targets based on time delays. An array of antennas is used in the approach, in which one antenna sends ultra-wide-band signals, and all antennas receive the signals backscattered by the targets. The time delays can be obtained by the interrelation of the transmitted and received signals. By controlling the timing of the pulses radiated from the individual antennas, high concentration of electromagnetic energy on the targets' locations can be achieved. The performance of this approach is demonstrated by several numerical simulations.
A Time-Domain Approach for the Fast Design of Reflector Impulse-Radiating Antennas
Ling-Lu Chen;Ju Feng;Lei Chang;Cheng Liao
PIER , 2013, DOI: 10.2528/PIER12111405
Abstract: It is difficult to determine the feed radiation center and F/D of the reflector impulse-radiating antenna (IRA) in frequencydomain, due to its ultra-wideband (UWB) property. This paper presents an efficient approach to design the reflector IRAs, via evaluating the transient radiation patterns (TRPs) of the feed for some given different radiation centers. Only one time-domain simulation for the feed is needed in this method. Comparing with the global optimization algorithms, our method is fast and reliable in the design of the reflector IRAs.
Hybrid-Surrogate-Model-Based Efficient Global Optimization for High-Dimensional Antenna Design
Ling-Lu Chen;Cheng Liao;Wenbin Lin;Lei Chang;Xuan-Ming Zhong
PIER , 2012, DOI: 10.2528/PIER11121203
Abstract: Efficient global optimization has been extensively used in problems with expensive cost functions. However, this method is not suitable for high-dimensional problems. In this paper, the radial basis function network is introduced into the efficient global optimization, to avoid local optima and achieve a fast convergence for high-dimensional optimization. Our algorithm is applied to a 12-dimensional optimization of a transmitting antenna. Compared to the genetic-algorithm-based efficient global optimization and the differential evolution strategy, our algorithm converges to the global optimal value more efficiently.
A Hybrid Method Based on Differential Evolution and Continuous Ant Colony Optimization and its Application on Wideband Antenna Design
Lei Chang;Cheng Liao;Wenbin Lin;Ling-Lu Chen;Xuan Zheng
PIER , 2012, DOI: 10.2528/PIER11092207
Abstract: An evolutionary learning algorithm based on differential evolution strategy (DES) and continuous ant colony optimization (CACO) for wideband antenna design is proposed. The advantages of this hybrid method are demonstrated with several mathematical functions and a linear array pattern synthesis. This method is applied to design an E-shaped wideband patch antenna, which achieves the impedance bandwidth 4.8 ~ 6.53 GHz. We compare the hybrid method with the traditional DES and CACO optimization algorithms, and the advantage of this hybrid method over the DES and the CACO is also demonstrated.
A Hybrid Optimized Algorithm Based on Ego and Taguchi's Method for Solving Expensive Evaluation Problems of Antenna Design
Nan Sheng;Cheng Liao;Wenbin Lin;Lei Chang;Qinghong Zhang;Haijing Zhou
PIER C , 2010, DOI: 10.2528/PIERC10091303
Abstract: In this paper, we propose a hybrid optimization approach that combines the Efficient Global Optimization (EGO) algorithm with Taguchi's method. This hybrid optimized algorithm is suited for problems with expensive cost functions. As a Bayesian analysis optimization algorithm, EGO algorithm begins with fitting the Kriging model with n sample points, and finds the (n+1)th point where the expected improvement is maximized to update the model. We employ Taguchi's method in EGO to obtain the (n+1)th point in this paper. A numerical simulation demonstrates that our algorithm has advantage over the original EGO. Finally, we apply this hybrid optimized algorithm to optimize an ultra-wide band (UWB) transverse electromagnetic (TEM) horn antenna and a linear antenna array. Compared to Taguchi's method and the Integer Coded Differential Evolution Strategy, our algorithm converges to the global optimal value more efficiently.
Design of an Ultra-Wideband Power Divider via the Coarse-Grained Parallel Micro-Genetic Algorithm
Lei Chang;Cheng Liao;Ling-Lu Chen;Wenbin Lin;Xuan Zheng;Yan-Liang Wu
PIER , 2012, DOI: 10.2528/PIER11120517
Abstract: An ultra-wideband (UWB) power divider is designed in this paper. The UWB performance of this power divider is obtained by using a tapered microstrip line that consists of exponential and elliptic sections. The coarse grained parallel micro-genetic algorithm (PMGA) and CST Microwave Studio are combined to achieve an automated parallel design process. The method is applied to optimize the UWB power divider. The optimized power divider is fabricated and measured. The measured results show relatively low insertion loss, good return loss, and high isolation between the output ports across the whole UWB (3.1-10.6 GHz).
Human IgG Subclasses against Enterovirus Type 71: Neutralization versus Antibody Dependent Enhancement of Infection
Rui-Yuan Cao, Da-Yong Dong, Rui-Ju Liu, Jian-Feng Han, Guang-Chuan Wang, Hui Zhao, Xiao-Feng Li, Yong-Qiang Deng, Shun-Ya Zhu, Xiao-Yu Wang, Fang Lin, Fu-Jun Zhang, Wei Chen, E-De Qin, Cheng-Feng Qin
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0064024
Abstract: The emerging human enterovirus 71 (EV71) represents a growing threat to public health, and no vaccine or specific antiviral is currently available. Human intravenous immunoglobulin (IVIG) is clinical used in treating severe EV71 infections. However, the discovery of antibody dependent enhancement (ADE) of EV71 infection illustrates the complex roles of antibody in controlling EV71 infection. In this study, to identify the distinct role of each IgG subclass on neutralization and enhancement of EV71 infection, different lots of pharmaceutical IVIG preparations manufactured from Chinese donors were used for IgG subclass fractionation by pH gradient elution with the protein A-conjugated affinity column. The neutralization and ADE capacities on EV71 infection of each purified IgG subclass were then assayed, respectively. The neutralizing activity of human IVIG is mainly mediated by IgG1 subclass and to less extent by IgG2 subclass. Interestingly, IgG3 fraction did not have neutralizing activity but enhanced EV71 infection in vitro. These results revealed the different roles of human IgG subclasses on EV71 infection, which is of critical importance for the rational design of immunotherapy and vaccines against severe EV71 diseases.
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