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Weihua Li,Yipeng Wang,Junlong Guo,Dianbo Ren,Jianfeng Wang,Shengkai Zhu,Jianping Xiao,Shijuan Chen 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.5
This study proposes an improved artificial potential field (APF) by considering the cooperative control of local obstacle avoidance and path tracking for automated vehicles. We established the path gravitational potential field (GPF) based on the scheduled path (SP), including the lateral and longitudinal GPFs, to enable the automated vehicle to quickly return to the SP and track after obstacle avoidance, while maintaining control of speed for the entire process. To address the local optimal solution problem of the classical APF, we proposed a sub-target-point selection strategy based on the information of obstacles and SP and established the GPF of the sub-target points. Thus, the automated vehicle can avoid obstacles and quickly return to the SP. Furthermore, the relative velocity of the automated vehicle and the obstacle was used to establish the velocity repulsion potential field (RPF), which improved the adaptability of the APF to dynamic obstacles. The simulation results indicate that the improved APF is capable of cooperative control of path tracking and local obstacle avoidance. Code is available at https://github.com/xiaowang617/Improve-APF.
Weihua Zhou,Yanbo Wangy,Zhe Chen 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
This paper presents a vector fitting (VF) algorithmbased gray-box structure and parameters identification method for voltage source converter(VSC). Terminal impedance frequency responses of VSC is first measured by frequency scanning method. Then, these impedance frequency responses are fitted by a polynomial transfer function using VF algorithm. Finally, the theoretical terminal impedance formulas of possible control structures are compared with the fitted transfer function. The actual control structure can be selected, and the actual internal parameters can be identified. Simulation results are given to validate effectiveness of the proposed method. The proposed gray-box method can identify both the circuit and controller information even if no internal information of the VSC is provided by vendors due to industrial confidence. In addition, the effect of measurement noise on parameters identification accuracy can be mitigated by increasing the order of the fitted transfer function.
Weihua Ni,Xu Zhang,Bo Wang,Yan Chen,Han Han,Yuying Fan,Yifa Zhou,Guihua Tai 한국식품영양과학회 2010 Journal of medicinal food Vol.13 No.2
A neutral polysaccharide fraction (WGPN) prepared from Panax ginseng C.A. Meyer by hot water extraction and DEAE-cellulose chromatography was tested for its anticancer activity alone and in combination with 5-fluorouracil (5-FU) in Sarcoma-180 (S180) tumor-bearing mice by intragastric administration. WGPN alone inhibited S180 tumor growth in a bell-shaped dose–response curve, and the combination with 5-FU showed a synergistic effect. Studies of various immunological activities in S180-bearing mice revealed that WGPN stimulated the proliferation of lymphocytes, increased natural killer cell cytotoxicity, enhanced the phagocytosis and nitric oxide production by macrophages, and increased the level of tumor necrosis factor-α in serum. In combination with 5-FU, WGPN mitigated damage to the immune system caused by 5-FU in S180-bearing mice. These results suggest that WGPN might be a potential adjuvant for chemotherapeutic drugs.
Performance analysis of two-dimensional DOA estimation for uniform circular array
Chen Liupeng,Mou Weihua,Lv Zhicheng,Zhang Yonghu,Hu Lizhi,Ou Gang 한국통신학회 2023 ICT Express Vol.9 No.5
Perturbation analysis of direction of arrival (DOA) estimation has been studied mostly on one-dimensional arrays rather than planar arrays, which remains room for exploration. For uniform circular arrays with various model errors, we establish the corresponding system model. Then a performance analysis of the two-dimensional MUSIC algorithm is proposed by first-order error analysis and verified by simulation. The results show that the root-mean-squared error of DOA estimation is proportional to the standard deviation of the model errors, including gain-phase errors, sensor position errors, and mutual coupling effect.
Ning Chen,Jiayang Dai,Xiaojun Zhou,Qingqing Yang,Weihua Gui 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.5
Iron precipitation is a key process in zinc hydrometallurgy. The process consists of a series of continuousreactors arranged in descending order, overflowing zinc leach solution from one reactor to the next. In this paper,according to the law of mass conservation and the reaction kinetics, a continuously stirred tank reactor model ofa single reactor is first established. Then, a distributed model of cascade reactors is built with coupled controlbased on the single reactor model, considering the unreacted oxygen in leaching solution. Secondly, four reactorsin the iron precipitation process are considered as four subsystems, the optimization control problem of the processis solved by a distributed model predictive control strategy. Moreover, the control information feedback betweensuccessive subsystems is used to solve the optimization problem of each subsystem, because of the existing controlcoupling in their optimization objective function of pre and post subsystems. Next, considering the intractability ofthe optimization problem for subsystems with various constraints, a distributed dual iterative algorithm is proposedto simplify the calculation. With the consideration of its cascade structure and control couplings, the proposedalgorithm iteratively solves the primal problem and the dual problem of each subsystem. The application case showsthat distributed model predictive control based on dual iteration algorithm can handle coupled control effectivelyand reduce the oxygen consumption.
A simple data assimilation method to improve atmospheric dispersion based on Lagrangian puff model
Li, Ke,Chen, Weihua,Liang, Manchun,Zhou, Jianqiu,Wang, Yunfu,He, Shuijun,Yang, Jie,Yang, Dandan,Shen, Hongmin,Wang, Xiangwei Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.7
To model the atmospheric dispersion of radionuclides released from nuclear accident is very important for nuclear emergency. But the uncertainty of model parameters, such as source term and meteorological data, may significantly affect the prediction accuracy. Data assimilation (DA) is usually used to improve the model prediction with the measurements. The paper proposed a parameter bias transformation method combined with Lagrangian puff model to perform DA. The method uses the transformation of coordinates to approximate the effect of parameters bias. The uncertainty of four model parameters is considered in the paper: release rate, wind speed, wind direction and plume height. And particle swarm optimization is used for searching the optimal parameters. Twin experiment and Kincaid experiment are used to evaluate the performance of the proposed method. The results show that the proposed method can effectively increase the reliability of model prediction and estimate the parameters. It has the advantage of clear concept and simple calculation. It will be useful for improving the result of atmospheric dispersion model at the early stage of nuclear emergency.
H∞ Synchronization of Two Different Discrete-Time Chaotic Systems via a Unified Model
Mei-Qin Liu,Haiyang Chen,Senlin Zhang,Weihua Sheng 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.1
This paper presents some novel synchronization methods for two discrete-time chaotic systems with different time delays, which are transformed into two unified models. First, the H∞ performance of the synchronization error dynamical system between the drive unified model and the response one is analyzed using the linear matrix inequality (LMI) approach. Second, the novel state feedback controllers are established to guarantee H∞ performance for the overall system. The parameters of these controllers are determined by solving the eigenvalue problem (EVP). Most discrete-time chaotic systems with or without time delays can be converted into this unified model, and H∞ synchronization controllers are designed in a unified way. The effectiveness of the proposed design methods are demonstrated by three numerical examples.
Hao Jia,Wei Chen,Xiuhua Wu,Shuai Li,Hong Liu,Jiru Liao,Weihua Liu,Mantian Mi,Longjian Liu,Daomei Cheng,Xiaoping Yu 대한수의학회 2013 Journal of Veterinary Science Vol.14 No.3
The effects of black rice anthocyanidins (BRACs) on retinal damage induced by photochemical stress are not well known. In the present study, Sprague-Dawley rats were fed AIN-93M for 1 week, after which 80 rats were randomly divided into two groups and treated with (n = 40) or without BRACs (n =40) for 15 days, respectively. After treatment, both groups were exposed to fluorescent light (3,000 ± 200 lux; 25oC), and the protective effect of dietary BRACs were evaluated afterwards. Our results showed that dietary BRACs effectively prevented retinal photochemical damage and inhibited the retinal cells apoptosis induced by fluorescent light (p < 0.05). Moreover, dietary BRACs inhibited expression of AP-1 (c-fos/c-jun subunits), up-regulated NF-κB (p65) expression and phosphorylation of IκB-α, and decreased Caspase-1 expression (p < 0.05). These results suggest that BRACs improve retinal damage produced by photochemical stress in rats via AP-1/NF-κB/Caspase-1apoptotic mechanisms.