Survey of Cognitive Radio VANET

( Xinxin He ),( Weisen Shi ),( Tao Luo ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.11

Vehicular Ad hoc Networks (VANET) becomes more popular in industry, academia and government. However, Typical VANET is challenged by high speed mobility and insufficient spectrum resources over congested scenarios. To address those serious problems, some articles have introduced Cognitive Radio (CR) technology into VANET and formed CR-VANET. In this article, we propose an overview of CR-VANET by exploring different architectures and features. Moreover, we provide taxonomy of state-of-the-art papers in this emerging field and the key articles are well analyzed respectively. In addition, we illustrate both research and application frameworks of CR-VANET based on our works, and propose some open research issues for inspiring future work.

Equivalent hysteresis model based SOC estimation with variable parameters considering temperature

He, Yao,Li, Qiang,Zheng, Xinxin,Liu, Xintian The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.3

Estimation of the state of charge (SOC) of a lithium-ion battery is one of the key technologies in battery management systems. The accuracy of SOC estimation mainly depends on the accuracy of the battery model. The traditional Thevenin model has limited application due to its fixed parameters. In addition, its accuracy is not high. This paper proposes a variable parameter equivalent hysteresis model based on the Thevenin model. The parameters of this model are regarded as variables that vary with temperature and SOC. They can be identified by hybrid pulse power characteristic (HPPC) experiments. In addition, the model also considers the hysteresis characteristics of the open circuit voltage (OCV) and uses a mathematical recursive equation to describe it. Experimental and simulation results show that the proposed model has a higher accuracy and a wider application than the Thevenin model. On the basis of this model, SOC estimation is carried out based on modified covariance extended Kalman filter (MVEKF) at different temperatures. The results show that the SOC estimation accuracy of the MVEKF method is significantly higher than that of an extended Kalman filter (EKF).

Primary Double Winding Coupling DC Transformer for DC Micro-Grid Applications

Zheng Xinxin,Pan Weijie,Liu Xintian,He Yao 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.3

In recent years, DC micro-grid has attracted widespread attention due to the signifi cant increase in DC loads and the demand for high-quality power. This paper proposes a novel primary double winding coupling topology of the DC transformer (DCT) for DC micro-grid applications. The primary side high-frequency full-bridge inverter is replaced by a novel topology without shoot-through problem. As a result, the reliability of the system is improved, and dead-time is unnecessary to be added to the driving signals thus the dc voltage utilization is higher. Compared to the no dead-time dual-buck inverter, the proposed topology has more advantages in the size and cost, because the primary two windings can be integrated on the same core. What’s more, the infl uence of the leakage inductance can be decreased by the parallel eff ect, so that the transmission effi - ciency of the DCT can be improved. In this paper, the evolution process of the non-dead zone and comparison with other topologies are given. The equivalent circuit and the compensation design are described in detail. The working principle and effi ciency of the proposed topology are analysed and calculated. The simulation and a simple prototype were built up for the experimental tests to verify the advancement of the proposed DCT.

Complex Current Controller Design Based on Multiple Equations Construction of Three-Phase Inverter

Zheng Xinxin,Sun Shangyuan,Liu Xintian,He Yao,Liu Yunbo 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.4

This paper proposes a complex PI current controller design method of three-phase inverter based on multiple equations construction. The mathematical model of three-phase inverter system plays an important role in the controller design process. In the synchronous reference frame, the inverter model introduces coupling elements, which is diff erent from the model in the stationary reference frame and brings diffi culty for current controller design. Complex vector model (CVM) is introduced in the current loop, which is established in the synchronous reference frame and takes part in the current controller design. Multiple equations construction is established to solve the parameters of the complex PI current controller. Because the controller satisfi es the restrictions of the multiple equations, it can realize good dynamic performance and the coupling characteristic of the three-phase system. In this paper, the CVM is established. The process of construct and solve the multiple equations is analyzed in detail. The accuracy of the inverter system is validated. Finally the simulation and experimental results are given to verify the theoretical analysis.

Cauchy mutation boosted Harris hawk algorithm: optimal performance design and engineering applications

Shan Weifeng,He Xinxin,Liu Haijun,Heidari Ali Asghar,Wang Maofa,Cai Zhennao,Chen Huiling 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.2

Harris hawks optimization (HHO) has been accepted as one of the well-established swarm-based methods in the community of optimization and machine learning that primarily works based on multiple dynamic features and various exploratory and exploitative traits. Compared with other optimization algorithms, it has been observed that HHO can obtain high-quality solutions for continuous and constrained complex and real-world problems. While there is a wide variety of strategies in the HHO for dealing with diverse situations, there are chances for sluggish performance, where the convergence rate can gradually slow with time, and the HHO may stay stuck in the current relatively better place and may be unable to explore other better areas. To mitigate this concern, this paper combines the Cauchy mutation mechanism into the HHO algorithm named CMHHO. This idea can boost performance and provide a promising optimizer for solving complex optimization problems. The Cauchy mutation mechanism can speed up the convergence of the solution and help HHO explore more promising regions compared to its basic release. On 30 IEEE CEC2017 benchmark functions, the study compared the proposed CMHHO with various conventional and advanced metaheuristics to validate its performance and quality of solutions. It has been found through experiments that the overall optimization performance of CMHHO is far superior to all competitors. The CMHHO method is applied to four engineering challenges to investigate the capabilities of the proposed algorithm in solving real-world problems, and experimental results show that the suggested algorithm is more successful than existing algorithms.

Passive Islanding Detection Method for Grid‑Connected Inverters Based on Closed‑Loop Frequency Control

Xintian Liu,Xinxin Zheng,Yao He,Guojian Zeng,Yanan Zhou 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.6

Islanding detection is one of the frontier research problems in the study of distributed grid. The non-detection zone of traditional passive detection method is large, and existing active detection methods for non-detection zones are complicated. Aiming at the above problems, this paper proposes a novel passive islanding detection method with the help of closed-loop frequency control (CFC). In this new method, a high-frequency impedance detection method is combined with CFC to prevent the occurrence of islanding, and the frequency tracking principle and high-frequency impedance characteristics of the CFC are analyzed. Load impedance characteristics under diferent islanding conditions are also discussed. Simulation and experimental results show that proposed method is able to detect the occurrence of inverter disconnection quickly and accurately, and non-detection zone is also eliminated.

Power control of CiADS core with the intensity of the proton beam

Kai Yin,Wenjing Ma,Wenjuan Cui,Zhiyong He,Xinxin Li,Shiwu Dang,Feng Yang,Yuhui Guo,Limin Duan,Meng Li,Yikai Hou 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.4

This paper reports the control method for the core power of the China initiative Accelerator DrivenSystem (CiADS) facility. In the CiADS facility, an intense external neutron source provided by a protonaccelerator coupled to a spallation target is used to drive a sub-critical reactor. Without any control rodinside the sub-critical reactor, the core power is controlled by adjusting the proton beam intensity. Inorder to continuously change the beam intensity, an adjustable aperture is considered to be used at theLow Energy Beam Transport (LEBT) line of the accelerator. The aperture size is adjusted based on theProportional Integral Derivative (PID) controllers, by comparing either the setting beam intensity or thesetting core power with the measured value. To evaluate the proposed control method, a CiADS coremodel is built based on the point reactor kinetics model with six delayed neutron groups. The simulations based on the CiADS core model have indicated that the core power can be controlled stably byadjusting the aperture size. The response time in the adjustment of the core power depends mainly onthe adjustment time of the beam intensity

Virtual Synchronous Generator Dynamic Decoupling Technology Based on Complex Vector Current Controller

Liu Xintian,Wang Ketian,Zheng Xinxin,He Yao 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.4

The concept of virtual synchronous generators (VSGs) is an eff ective means for improving the stable operation of the grid when the large number of distributed power sources connected to the grid. However, due to its power coupling problem, coupling overshoot and steady-state error occur during power adjustment, which seriously aff ects the dynamic performance and stability of the system. With this problem in mind, the system model of VSG is established by using a complex vector analysis method. Then the coupling system is analyzed by the bilateral frequency response characteristic curve and pole-zero diagram. On this basis, a dynamic decoupling method based on complex vectors is proposed. Decoupling is obtained by eliminating the poles of the controlled object through the zero points of the controller. After decoupling, when the system performs active power adjustment, the reactive power coupling overshoot is reduced by 83% and the steady-state error is completely eliminated. When the system performs reactive power adjustment, the active power coupling overshoot is reduced by 80%, the dynamic performance and stability of the system have been improved. Simulation and experimental is used to verify the theoretical analysis

Modular multilevel converter predictive control strategy based on energy balance

Xia, Xiangyang,Xu, Lei,Zhao, Xinxin,Zeng, Xiaoyong,Zhang, Jing,He, Yedan,Yi, Haigan The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.5

In MMC-HVDC (modular multilevel converter-based high-voltage direct current) applications, conventional control methods have defects such as complicated control and difficulty in controlling the internal energy of the converter. To ensure the safe and stable operation of an MMC-HVDC system, the problem of uneven internal energy distribution and increased fluctuations in the modular multilevel converter under asymmetrical network voltage conditions must be addressed. This paper has designed, a novel model predictive control (MPC) for MMC-HVDC applications. Through the proposed strategy, the switching states of all the MMC units can be optimized, which eliminates the circulating currents and achieves a voltage balance of the capacitor by redundant switching states. Moreover, an energy control circuit is established to adjust the DC bus power distribution in the MMC three-phase bridge arm. Thus, the symmetrical ac-side current can be realized, and the MMC internal energy imbalance caused by the transient process of the system can be avoided. Finally, the proposed novel predictive control strategy is tested via a case study. The obtained simulation and experimental results verify the effectiveness of the proposed control strategy.

Enrichment of C17:0-rich saturated fatty acids from sheep tail fat for adjuvant therapy of non-small-cell lung cancer

Xiaoqi Yu,Xiaoyi Liu,Yuanli Li,Huimin He,Xinxin Pei,Tengfei Ma,Yuanyuan Chen,Yi Wang,Hongxia Li,Wenchu Lin,Changzhi Xu,Buchang Zhang 한국식품과학회 2024 Food Science and Biotechnology Vol.33 No.8

Heptadecanoic acid (C17:0), an odd-chain saturated fatty acid (OCSFA) in ruminant lipid, has been demonstrated to be potential for treating cancers. Our results also showed that sheep tail fat (STF) with higher level of C17:0-containing saturated fatty acids (SFAs) whereas lower level of oleic acid (C18:1), performed remarkable inhibition against non-small-cell lung cancer (NSCLC) cells. To enrich the content of C17:0, a C17:0-rich SFA concentrate (HRSC) was prepared from STF by solvent crystallization and urea complexation methods (hexane/STF = 3.5/1, 4 °C for 8 h, and 80% ethanol/urea/free fatty acids = 8/1/1, 4 °C for 6 h). The content of C17:0 was up from 3.02 to 6.34% and the recovery was 4.17%. Biological experiments showed that HRSC exerted better antiproliferative effect against NSCLC cells. Moreover, HRSC performed enhanced inhibitory effect in A549 cell xenograft mouse model. Therefore, HRSC has the potential to be applied in adjuvant therapy for NSCLC.