Filter-based Immersion and Invariance Adaptive Control of Nonlinear Systems

Wei Chen,Jian Hu,Jianyong Yao,Weirong Nie,Haibo Zhou 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.1

This paper proposes a novel filter-based immersion and invariance (I&I) adaptive method for nonlinear systems with additive disturbances and parameter uncertainties. The key innovation of the proposed method is a filter construction that involves the dynamics of the system, based on which the I&I parameter estimator with a sigma modification term is designed. Comparing existing I&I methods, the expression for the novel filter-based I&I estimator is given in terms of total derivatives rather than partial derivatives, which is no longer subject to the integrability condition. In combining the sigma modification term, the proposed parameter estimator also guarantee the uniformly ultimately bounded stability of the parameter estimation error when the system is disturbed, which cannot be achieved by the original I&I method. Furthermore, Lyapunov theory demonstrates that the proposed method can guarantee the stability of the nonlinear systems discussed in this paper. Simulation and experimental results confirm the effectiveness of the proposed method.

Experimental and Numerical Comparative Study on Gravity Dam-Reservoir Coupling System

Mingming Wang,Jianyun Chen,Weirong Xiao 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.10

A 203m high gravity dam-reservoir coupling system in earthquake is studied experimentally and numerically in this work. The dynamic model test is performed on a shaking table, and the dynamic process of the coupling system is simulated with two numerical methods. The natural frequency, hydrodynamic pressure on upstream and acceleration amplification factors along the dam height are obtained from the test and the methods. It is found that the results from FSCM agree better with those from test compared with AMM. So the FSCM should be the first choice to analysis the dam-reservoir coupling system interaction under earthquake. The AMM, which is frequently used in the Code for Seismic Design of Hydraulic Structures of many countries, needs to be modified by a factor smaller than 1. The factor varies along the height of the dam according to its shape, reservoir depth and higher modes and so on. Finally, the reduction factors of the AMM along dam height are suggested in this work.

Long non-coding RNA T-cell leukemia/lymphoma 6 serves as a sponge for miR-21 modulating the cell proliferation of retinoblastoma through PTEN

Tao, Sisi,Wang, Weidong,Liu, Pengfei,Wang, Hua,Chen, Weirong The Korean Society of Pharmacology 2019 The Korean Journal of Physiology & Pharmacology Vol.23 No.6

Retinoblastoma (Rb) is one of the most common eye malignancies occur in childhood. The crucial roles of non-coding RNAs, particularly long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), have been widely reported in Rb progression. In the present study, we found the expression of lncRNA T-cell leukemia/lymphoma 6 (TCL6) was significantly downregulated in Rb tissues and cell lines. Knockdown of lncRNA TCL6 promoted cell proliferation while reduced cell apoptosis in Rb cells. Moreover, lncRNA TCL6 serves as a sponge for miR-21, a previously-reported oncogenic miRNA in Rb, by direct targeting to negatively regulated miR-21 expression, therefore modulating Rb proliferation through miR-21. TCL6 overexpression inhibited Rb cell proliferation while miR-21 overexpression exerted an opposing effect; the effect of TCL6 overexpression was partially attenuated by miR-21 overexpression. PTEN/PI3K/AKT signaling pathway was involved in lncRNA TCL6/miR-21 axis modulating Rb cell proliferation. Taken together, lncRNA TCL6 serves as a tumor suppressor by acting as a sponge for miR-21 to counteract miR-21-mediated PTEN repression.

Low Frequency Current Ripple Mitigation of Two Stage Three-Phase PEMFC Generation Systems

Huiwen Deng,Qi Li,Zhixiang Liu,Lun Li,Weirong Chen 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

This paper presents a two stage three-phase proton exchange membrane fuel cell (PEMFC) generation system. When the system is connected to a three-phase load, it is very sensitive to the characteristics and type of the load. Especially unbalanced three-phase loads, which result in a pulsating power that is twice the output frequency at the inverter output, and cause the dc-link to generate low frequency ripples. This penetrates to the fuel cell side through the front-end dc-dc converter, which makes the fuel cell work in an unsafe condition and degrades its lifespan. In this paper, the generation and propagation mechanism of low frequency ripple is analyzed and its impact on fuel cells is presented based on the PEMFC output characteristics model. Then a novel method to evaluate low frequency current ripple control capability is investigated. Moreover, a control scheme with bandpass filter inserted into the current feed-forward path, and ripple duty ratio compensation based on current mode control with notch filter is also proposed to achieve low frequency ripple suppression and dynamic characteristics improvement during load transients. Finally, different control methods are verified and compared by simulation and experimental results.

Low Frequency Current Ripple Mitigation of Two Stage Three-Phase PEMFC Generation Systems

Deng, Huiwen,Li, Qi,Liu, Zhixiang,Li, Lun,Chen, Weirong The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

This paper presents a two stage three-phase proton exchange membrane fuel cell (PEMFC) generation system. When the system is connected to a three-phase load, it is very sensitive to the characteristics and type of the load. Especially unbalanced three-phase loads, which result in a pulsating power that is twice the output frequency at the inverter output, and cause the dc-link to generate low frequency ripples. This penetrates to the fuel cell side through the front-end dc-dc converter, which makes the fuel cell work in an unsafe condition and degrades its lifespan. In this paper, the generation and propagation mechanism of low frequency ripple is analyzed and its impact on fuel cells is presented based on the PEMFC output characteristics model. Then a novel method to evaluate low frequency current ripple control capability is investigated. Moreover, a control scheme with bandpass filter inserted into the current feed-forward path, and ripple duty ratio compensation based on current mode control with notch filter is also proposed to achieve low frequency ripple suppression and dynamic characteristics improvement during load transients. Finally, different control methods are verified and compared by simulation and experimental results.

Long non-coding RNA T-cell leukemia/lymphoma 6 serves as a sponge for miR-21 modulating the cell proliferation of retinoblastoma through PTEN

Sisi Tao,Weidong Wang,Pengfei Liu,Hua Wang,Weirong Chen 대한약리학회 2019 The Korean Journal of Physiology & Pharmacology Vol.23 No.6

Retinoblastoma (Rb) is one of the most common eye malignancies occur in childhood. The crucial roles of non-coding RNAs, particularly long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), have been widely reported in Rb progression. In the present study, we found the expression of lncRNA T-cell leukemia/lymphoma 6 (TCL6) was significantly downregulated in Rb tissues and cell lines. Knockdown of lncRNA TCL6 promoted cell proliferation while reduced cell apoptosis in Rb cells. Moreover, lncRNA TCL6 serves as a sponge for miR-21, a previously-reported oncogenic miRNA in Rb, by direct targeting to negatively regulated miR-21 expression, therefore modulating Rb proliferation through miR-21. TCL6 overexpression inhibited Rb cell proliferation while miR-21 overexpression exerted an opposing effect; the effect of TCL6 overexpression was partially attenuated by miR-21 overexpression. PTEN/PI3K/AKT signaling pathway was involved in lncRNA TCL6/miR-21 axis modulating Rb cell proliferation. Taken together, lncRNA TCL6 serves as a tumor suppressor by acting as a sponge for miR-21 to counteract miR-21-mediated PTEN repression.