Dual-Band Antenna with OAM Mode Radiated by Ground Plane

Li Yuheng,Yang Guang,Li Weiwen,Liu Qing Huo 한국전자파학회 2023 Journal of Electromagnetic Engineering and Science Vol.23 No.3

Antennas that radiate orbital angular momentum (OAM) modes are usually large and have complex structures. In this paper, in combination with characteristic mode analysis, the ground plane is used as the OAM wave radiator. To excite degenerate modes of the ground plane with phase quadrature by using a single-fed structure, two bent metal strips with grounded ends are introduced around the rectangular ground plane, and a corner of one of the bent strips is set as the feeding point. For ground radiators, a first-order OAM mode is generated at the high-frequency end by synthesizing the degenerate modes. In case of the bent side strip, an inverted-F antenna that operates in the low-frequency mode is formed. This compact antenna has dual-band characteristics and facilitates simple feeding, which makes it suitable for mobile terminal applications.

RESEARCH ON MILLIMETER WAVE RADAR SIMULATION MODEL FOR INTELLIGENT VEHICLE

Xin Li,Weiwen Deng,Sumin Zhang,Yaxin Li,Shiping Song,Shanshan Wang,Guanyu Wang 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.2

Radar simulation models can effectively overcome the drawbacks of real vehicle experiment and speed up the development process of intelligent vehicle technologies based on millimeter wave radar via virtual testing. However, there are still many gaps between the radar model using in the virtual driving environment and the real radar. In this paper, a novel simulation model of intelligent vehicle millimeter wave radar is proposed. Based on the analysis of the real radar performance in typical application scenes, the radar model considers the mechanism and characteristics of the vehicle radar synthetically and a systematic radar modeling architecture with innovation is introduced. The highlights of this radar model include the design of the RCS simulation model for radar targets with both high accuracy and real-time performance, the establishment of the quantitative false alarm model, missed detection model and measurement error simulation model. Vast amounts of data collected by real vehicle radar are applied to fetch model parameters and verify the accuracy of the radar model. Simulation results show that the proposed model can reach both high reliability and computational efficiency.

Human dynamics based driver model for autonomous car

Li, Lin,Liu, Yanheng,Wang, Jian,Deng, Weiwen,Oh, Heekuck IET 2016 IET intelligent transport systems Vol.10 No.8

<P>This study presents a new driver model based on human behaviour dynamics for autonomous cars, which allows driverless cars to move appropriately in accordance to the behavioural features of driver owners. This model is established through analysing drivers' various properties, e.g. gender, age, driving experience, personality, and emotion. These attributes collectively determine all the actions occurred during the driving process. Through analysing the statistical data gathered during the simulation, the authors find that the proposed model can reflect the power-law distribution with respect to the concerned human behaviours. Finally, the proposed model is validated by the hardware-in-loop simulator and real driving experiment.</P>

A Bayesian optimal design for degradation tests based on the inverse Gaussian process

Weiwen Peng,Yu Liu,Yanfeng Li,Shun-Peng Zhu,Hong-Zhong Huang 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.10

The inverse Gaussian process is recently introduced as an attractive and flexible stochastic process for degradation modeling. This processhas been demonstrated as a valuable complement for models that are developed on the basis of the Wiener and gamma processes. We investigate the optimal design of the degradation tests on the basis of the inverse Gaussian process. In addition to an optimal designwith pre-estimated planning values of model parameters, we also address the issue of uncertainty in the planning values by using theBayesian method. An average pre-posterior variance of reliability is used as the optimization criterion. A trade-off between sample sizeand number of degradation observations is investigated in the degradation test planning. The effects of priors on the optimal designs andon the value of prior information are also investigated and quantified. The degradation test planning of a GaAs Laser device is performedto demonstrate the proposed method.

Evolutionary Rates and Phylogeographical Analysis of Odontoglossum Ringspot Virus Based on the 166 Coat Protein Gene Sequences

Zhen He,Tingting Dong,Weiwen Wu,Wen Chen,Xian Liu,Liangjun Li 한국식물병리학회 2019 Plant Pathology Journal Vol.35 No.5

Odontoglossum ringspot virus (ORSV) is a member of the genus Tobamovirus. It is one of the most prevalent viruses infecting orchids worldwide. Earlier studies reported the genetic variability of ORSV isolates from Korea and China. However, the evolutionary rate, timescale, and phylogeographical analyses of ORSV were unclear. Twenty-one coat protein (CP) gene sequences of ORSV were determined in this study, and used them together with 145 CP sequences obtained from GenBank to infer the genetic diversities, evolutionary rate, timescale and migration of ORSV populations. Evolutionary rate of ORSV populations was 1.25 × 10−3 nucleotides/site/y. The most recent common ancestors came from 30 year ago (95% confidence intervals, 26- 40). Based on CP gene, ORSV migrated from mainland China and South Korea to Taiwan island, Germany, Australia, Singapore, and Indonesia, and it also circulated within east Asia. Our study is the first attempt to evaluate the evolutionary rates, timescales and migration dynamics of ORSV.

Disturbance rejection speed sensorless control of PMSMs based on full order adaptive observer

Xu, Yanping,Wang, Li,Yuan, Weiwen,Yin, Zhonggang The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.5

Speed sensorless control systems with a full order adaptive observer of the permanent magnet synchronous motor (PMSM) have received wide attention due to their advantages of simple structure, easy implementation and strong universality. However, they are sensitive to the load disturbances, which affects the speed performance of the control system. To solve this problem, this paper presents a disturbance rejection speed sensorless control of PMSMs based on full order adaptive observer to improve robustness against load disturbances. A load disturbance observer (LDO) is used to observe load disturbances, which feed-forward compensates the q-axis current to reduce the speed drop and accelerate the recovery time. Experimental results show that the proposed method has better anti-interference capability than full order adaptive speed sensorless control under the same steady-state performance.

Experimental behavior of VHSC encased composite stub column under compression and end moment

Zhenyu Huang,Xinxiong Huang,Weiwen Li,Liu Mei,J.Y. Richard Liew 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.1

This paper investigates the structural behavior of very high strength concrete encased steel composite columns via combined experimental and analytical study. The experimental programme examines stub composite columns under pure compression and eccentric compression. The experimental results show that the high strength encased concrete composite column exhibits brittle post peak behavior and low ductility but has acceptable compressive resistance. The high strength concrete encased composite column subjected to early spalling and initial flexural cracking due to its brittle nature that may degrade the stiffness and ultimate resistance. The analytical study compares the current code methods (ACI 318, Eurocode 4, AISC 360 and Chinese JGJ 138) in predicting the compressive resistance of the high strength concrete encased composite columns to verify the accuracy. The plastic design resistance may not be fully achieved. A database including the concrete encased composite column under concentered and eccentric compression is established to verify the predictions using the proposed elastic, elastoplastic and plastic methods. Image-oriented intelligent recognition tool-based fiber element method is programmed to predict the load resistances. It is found that the plastic method can give an accurate prediction of the load resistance for the encased composite column using normal strength concrete (20-60 MPa) while the elastoplastic method provides reasonably conservative predictions for the encased composite column using high strength concrete (60-120 MPa).

An Intention-aware and Online Driving Style Estimation Based Personalized Autonomous Driving Strategy

Sun Bohua,Deng Weiwen,Wu Jian,Li Yaxin,Wang Jinsong 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.6

Autonomous vehicles are aiming at improving driving safety and comfort. They need to perform socially accepted behaviors in complex urban scenarios including human-driven vehicles with uncertain intentions. What’s more, understanding human drivers’ driving styles that make the systems more human-like or personalized is the key to improve the system performance, in particular, the acceptance and adaption of autonomous vehicles to human passengers. In this study, a personalized intention-aware autonomous driving strategy is proposed. An online driving style identification is proposed based on double-level Multi-dimension Gaussian Hidden Markov Process (MGHMP) with arbitration mechanism and evaluated in field test. A Mixed Observable Markov Decision Process (MOMDP) is built to model the general personalized intention-aware framework. A human-like policy generation mechanism is used to generate the possible candidates to overcome the difficulty in solving MOMDP. The index of surrounding vehicles’ intention of the upper-level MGHMP is updated during each prediction time step. The weighting factors of the reward function are configured with the identification result of lower-level MGHMP. The personalized intention-aware autonomous driving strategy is evaluated on a Real-Time Intelligent Simulation Platform. Results show that the proposed strategy can achieve the online identification accuracy above 95 % and for personalized autonomous driving in scenarios mixed with human-driven vehicles with uncertain intentions.

Compressive resistance behavior of UHPFRC encased steel composite stub column

Zhenyu Huang,Xinxiong Huang,Weiwen Li,Jiasheng Zhang 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.2

To explore the feasibility of eliminating the longitudinal rebars and stirrups by using ultra-high-performance fiber reinforcement concrete (UHPFRC) in concrete encased steel composite stub column, compressive behavior of UHPFRC encased steel stub column has been experimentally investigated. Effect of concrete types (normal strength concrete, high strength concrete and UHPFRC), fiber fractions, and transverse reinforcement ratio on failure mode, ductility behavior and axial compressive resistance of composite columns have been quantified through axial compression tests. The experimental results show that concrete encased composite columns with NSC and HSC exhibit concrete crushing and spalling failure, respectively, while composite columns using UHPFRC exhibit concrete spitting and no concrete spalling is observed after failure. The incorporation of steel fiber as micro reinforcement significantly improves the concrete toughness, restrains the crack propagation and thus avoids the concrete spalling. No evidence of local buckling of rebars or yielding of stirrups has been detected in composite columns using UHPFRC. Steel fibers improve the bond strength between the concrete and, rebars and core shaped steel which contribute to the improvement of confining pressure on concrete. Three prediction models in Eurocode 4, AISC 360 and JGJ 138 and a proposed toughness index (T.I.) are employed to evaluate the compressive resistance and post peak ductility of the composite columns. It is found that all these three models predict close the compressive resistance of UHPFRC encased composite columns with/without the transverse reinforcement. UHPFRC encased composite columns can achieve a comparable level of ductility with the reinforced concrete (RC) columns using normal strength concrete. In terms of compressive resistance behavior, the feasibility of UHPFRC encased steel composite stub columns with lesser longitudinal reinforcement and stirrups has been verified in this study.

Evolutionary Rates and Phylogeographical Analysis of Odontoglossum Ringspot Virus Based on the 166 Coat Protein Gene Sequences

He, Zhen,Dong, Tingting,Wu, Weiwen,Chen, Wen,Liu, Xian,Li, Liangjun The Korean Society of Plant Pathology 2019 Plant Pathology Journal Vol.35 No.5

Odontoglossum ringspot virus (ORSV) is a member of the genus Tobamovirus. It is one of the most prevalent viruses infecting orchids worldwide. Earlier studies reported the genetic variability of ORSV isolates from Korea and China. However, the evolutionary rate, timescale, and phylogeographical analyses of ORSV were unclear. Twenty-one coat protein (CP) gene sequences of ORSV were determined in this study, and used them together with 145 CP sequences obtained from GenBank to infer the genetic diversities, evolutionary rate, timescale and migration of ORSV populations. Evolutionary rate of ORSV populations was $1.25{\times}10^{-3}nucleotides/site/y$. The most recent common ancestors came from 30 year ago (95% confidence intervals, 26-40). Based on CP gene, ORSV migrated from mainland China and South Korea to Taiwan island, Germany, Australia, Singapore, and Indonesia, and it also circulated within east Asia. Our study is the first attempt to evaluate the evolutionary rates, timescales and migration dynamics of ORSV.