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Quantitative Analysis of Critical Limitation in Using Extended State Observer
Mingwei Sun,Yi Li,Zenghui Wang,Zengqiang Chen 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.3
Active disturbance rejection control (ADRC) has been successfully widely applied. The extended stateobserver (ESO) is a crucial component of ADRC to deal with uncertainties in many control systems. Althoughthe nominal stability of ADRC was proved by adopting a sufficiently fast observer with a performance recoveryprinciple, it is difficult to be employed in practice because severe oscillation or even instability might be triggeredif the fast observer was used. This paper investigates the reason behind this phenomenon within the frameworkof input time-delay sensitivity for a typical first-order system, which can provide an insightful understanding ofADRC. The positive root of the polynomial which determines the maximal input time-delay maintaining closed loopstability is quantitatively analyzed and the relationship among the bandwidth of ESO, other control parametersand the allowable input time-delay is thoroughly studied. Finally, numerical examples are presented to validate thecorresponding theoretical results.
Lirong Sun,Zhongyi Cai,Jiaxin Gao,Mingwei Wang,Li Li 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.4
This paper is concerned with accurate prediction on the fracture strain and fracture forming limit curve (FFLC) by calibratingthe material constants by the specimens with reasonable shapes and sizes. The Lou–Huh ductile fracture criteria (DFC)in analytic and integral forms were adopted, and the theoretical formulas in various stress states were derived. The processand basis for calibrating the material constants of DFC by hybrid experimental–numerical method were described in detail. Moreover, the material constants calculated by different test groups including the uniaxial tensile, plane strain and shearspecimens with different shapes and sizes vary enormously, and the optimal test group was determined to calibrate the materialconstant of DFC. Meanwhile, it can be found that the different material constants greatly impact on the magnitude andshape of the fracture strain and FFLC, and the effect of each material constant on the fracture strain and FFLC was analyzedand compared in this paper. Finally, the FFLCs theoretically calculated by DFC in analytic and integral forms were verifiedby the experimental forming limiting data of the bulge test.
Junhong Chen,Mingwei Yan, Yong Li,Zhijian Li,Jindong Su,Bin Li,Jialin Sun 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.5
Periclase-hercynite bricks were prepared from fused or reaction-sintered hercynite. The microstructure of the obtained brickswas studied and their thermal conductivity in the simulated on-site condition was tested. The results show that the mutualdiffusion of Fe or Al from hercynite and Mg from periclase forms more pores in the material. Compared with the brickprepared from fused hercynite, the brick from reaction-sintered hercynite has smaller pore size. The thermal conductivitysimulation test of the two bricks at 1550 oC shows that the cold end temperature of the brick synthesized from the reactionsinteredhercynite is 40 oC lower than that of the brick from the fused hercynite. Thus, in consideration of reducing the shelltemperature of the cement rotary kilns, the reaction-sintered hercynite is more favorable for the production of periclasehercynitebricks.
Zhihu Yan,Caili Dai,Mingwei Zhao,Yongpeng Sun,Guang Zhao 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.37 No.-
Through extensive experiments, a reusable viscoelastic surfactant (rVES) fracturing fluid using a selfdesignedand synthesized surfactant was developed. Laboratory performance evaluation results showedthat various performances of rVES fracturing fluid are excellent. The most attractive aspect is the gellingand gel breaking of rVES fracturing fluid was achieved by altering the pH value. The recycled fracturingfluid still maintains good performances through three times cycles, which represents that it has goodprospects for re-use of flowback waters. In addition, large-scale coarse-grained molecular dynamics(CGMD) simulations results clearly revealed the formation mechanism of rVES fracturing fluid at themolecular level.
Yunxi Zhang,Yu Fan,Mingwei Sun,Zenghui Wang,Zengqiang Chen 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.1
The high-speed anti-ship missile might encounter a challenge in the terminal phase if there are mixed targets, including false and true ones. There is only a quite short time to take action after the onboard radar can distinguish which targets are true or false. In this study, a tunable acceleration feedback gain is used to realize a unique integrated guidance and control scheme in a natural way by maintaining advantages of the traditionally practical proportional navigation and three-loop acceleration autopilot without introducing additional dynamics as the existing methods in the literature. The gain range can be determined using a numerical calculation scheme. The adjoint method is employed to reveal the advantage of the tunable gain and can then obtain the optimal gain. The proposed method can achieve a trade-off between the effective navigation gain and the settling time of the autopilot during the integration. Extensive simulations are performed to validate the appealing discovery. This philosophy offers guideline for the renovation of existing anti-ship missiles.
Quanwu Wen,Shaohua Zhang,Mingwei Sun,Rencheng Jin 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.5
Transition metal oxides as Li-ion batteries (LIBs) anodes have attracted much attention because of their high theoretical capacity. However, the large volume change and low electrical conductivity still hinder their application in LIBs. In this work, a new strategy is proposed to enhance the electrochemical performance by anchoring ultrafine MnFe2O4 and MnCO3 (~5 nm) on amorphous carbon-coated carbon nanotubes. Benefiting from the unique structure, the electrode displays excellent cyclability with a reversible specific capacity of 1012mAh g -1 at 0.1A g -1 after 100 cycles and outstanding rate performance accompanied by a high specific capacity of 568mAh g -1 at 5A g -1 as anode for lithium batteries. When evaluated as supercapacitors, the electrode delivers the specific capacitance of 588.9 F g -1 at a current density of 1A g -1 and maintains the capacitance retention 94.7% after 4000 cycles at 5A g -1.
Structure of hercynite prepared with existence of metal Fe
Junhong Chen,Dongfang Liu,Mingwei Yan, Yong Li,Jindong Su,Bin Li,Jialin Sun 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.12
In this work, raw materials analytically pure Al2O3 and analytically pure Fe2O3 were mixed in FeO: Al2O3 molar ratio of 1 : 1and pressed into specimens. The specimens were embedded in analytically pure metal Fe powders and fired slowly to 1650 oCin air atmosphere, and then soaked at 1650 oC for 5 hrs. The fired specimens were investigated by XRD, SEM, and EDS. Theresults show that the specimen synthesized at high temperatures in melting Fe is composed of hercynite and wüstite (FenO(n ≤ 1)); FenO disperses in hercynite; hercynite crystals develop well and are mostly perfect octahedron with grain size around50μm. The hercynite has Fe/Al ratio smaller than 1/2, which is non-stoichimetric. With the existence of melting Fe, althoughthe raw materials are theoretically batched according to FeO·Al2O3, FenO is still excess, so the hercynite obtained is Al-rich.
Grey Wolf Optimization based Active Disturbance Rejection Control Parameter Tuning for Ship Course
Jia Ren,Zengqiang Chen,Yikang Yang,Mingwei Sun,Qinglin Sun,Zenghui Wang 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.3
It is important to control the ship course in complicated ocean environment. In this paper, a Grey Wolf Optimization (GWO) based Active Disturbance Rejection Control (ADRC) tuning method is proposed in the application of the ship course. Here, GWO is used to tune the parameters of ADRC. To validate the performance of the proposed method, some simulations have been carried out and the results are compared with the results of other tuning methods, such as, Harris Hawks Optimization (HHO), Particle Swarm Optimization (PSO), Q-learning and manual tuning. To test the stability of different tuning methods, the cases of no disturbance, constant value disturbance, second-order wave force disturbance, white noise disturbance and mixed disturbance are considered. The robustness of the system for parameters perturbation is analyzed. The research indicates that the GWO based ADRC can achieve better performance than other methods.
Juan Xiao,Shuyi Li,Yong Sui,Xiaopeng Li,Qian Wu,Ruifen Zhang,Mingwei Zhang,Bijun Xie,Zhida Sun 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.4
The antioxidant activity of proanthocyanidins extracted from the lotus seedpods (LSPC) in vitro and ameliorative effects on memory impairment induced using scopolamine in mice were studied. 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging ability, oxygen radical absorbance capacity, and cellular antioxidant activity assays revealed a potent LSPC antioxidant activity. Y-maze and step-down avoidance testing showed that LSPC administration at 30, 60, and 90 mg/kg ameliorated memory impairment. LSPC improved glutathione peroxidase and superoxide dismutase activities, inhibited activities of monoamine oxidase-B, total nitric oxide synthase, neuronal nitric oxide synthase, and acetylcholinesterase, and had no influence on inducible nitric oxide synthase and nitric oxide levels in the brain. LSPC ameliorated scopolamineinduced memory impairment based on improvement of the antioxidant system and cholinergic activity, which may be associated with potent antioxidant ability.