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Guoqing Xia,Chuang Sun,Bo Zhao,Jingjing Xue 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.2
This paper presents a new cooperative control strategy for dynamic positioning of multiple surface vesselssubject to unknown time-varying environmental disturbances and input saturation. The vessels are assumedinterconnected through a directed topology rather than bidirectional. Two control objectives are considered in thispaper. The first one is to make these vessels track desired positions and headings, and the other control objective isto hold the desired formation. For these purposes, we propose a cooperative control which consists of finite-timedisturbance observer, auxiliary dynamic system and dynamic surface control technique. A nonlinear finite-timeobserver is developed to estimate unknown time-varying disturbance. To tackle the input saturation problem, anauxiliary dynamic system is constructed. It is also proved that all signals in the closed-loop control system convergeto a small neighborhood of equilibrium state via Lyapunov analysis. Simulation results are given to validate theeffectiveness of the proposed control strategy.
Guoqing Xia,Caiyun Liu,Bo Zhao,Xinghua Chen,Xingchao Shao 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.11
This paper investigates finite-time output feedback control for ship dynamic positioning assisted mooring system with external disturbances and without velocity measurement. Firstly, a finite-time observer is designed to estimate the velocity of the positioning ship and the external disturbances. Secondly, based on the proposed observer, a finite-time control law is introduced to bring the ship to the desired position and heading. Furthermore, the stability of the overall closed-loop system is proved by using matrix inequality, homogeneous and Lyapunov stability theory. Finally, the effectiveness of the proposed positioning control is verified by numerical simulations.
Preparation and thermo-mechanical properties of heat-resistant epoxy/silica hybrid materials
Yang, Peng,Wang, Guoqing,Xia, Xue,Takezawa, Yoshitaka,Wang, Haitao,Yamada, Shinji,Du, Qiangguo,Zhong, Wei Wiley Subscription Services, Inc., A Wiley Company 2008 Polymer engineering and science Vol.48 No.6
<P>Diglycidyl ether of bisphenol-A (DGEBA) based epoxy/silica hybrid materials filled with various amounts of 3-glycidoxypropyltrimethoxysilane (GPTMS) and silica nanoparticles were prepared, using 4,4′-diaminodiphenyl sulfone (DDS) as curing agent. The obtained hybrid materials were analyzed by means of Fourier-transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results indicated that the introduction of GPTMS and silica nanoparticles had synergistic effect. The addition of GPTMS not only ameliorated the compatibility between silica and the epoxy matrix but also increased the crosslinking density of the epoxy system; meanwhile the nano-silica further reinforced the inorganic network of the hybrid system. Consequently, the hybrid materials showed much improved heat-resistant properties. The storage modulus of the hybrid systems showed no obvious decrement in the glass transition region and kept at a high value even in the temperature region up to 300°C. The integral thermal stability of the resulting hybrid materials was also improved compared with the corresponding pure epoxy resin. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.</P>
Kurokawa, Kenji,Jung, Dong-Jun,An, Jang-Hyun,Fuchs, Katharina,Jeon, Yu-Jin,Kim, Na-Hyang,Li, Xuehua,Tateishi, Koichiro,Park, Ji Ae,Xia, Guoqing,Matsushita, Misao,Takahashi, Kazue,Park, Hee-Ju,Peschel, American Society for Biochemistry and Molecular Bi 2013 The Journal of biological chemistry Vol.288 No.43
<P>Serum antibodies and mannose-binding lectin (MBL) are important host defense factors for host adaptive and innate immunity, respectively. Antibodies and MBL also initiate the classical and lectin complement pathways, respectively, leading to opsonophagocytosis. We have shown previously that <I>Staphylococcus aureus</I> wall teichoic acid (WTA), a cell wall glycopolymer consisting of ribitol phosphate substituted with α- or β-<I>O-N</I>-acetyl-<SMALL>d</SMALL>-glucosamine (GlcNAc) and <SMALL>d</SMALL>-alanine, is recognized by MBL and serum anti-WTA IgG. However, the exact antigenic determinants to which anti-WTA antibodies or MBL bind have not been determined. To answer this question, several <I>S. aureus</I> mutants, such as α-GlcNAc glycosyltransferase-deficient <I>S. aureus</I> Δ<I>tarM</I>, β-GlcNAc glycosyltransferase-deficient Δ<I>tarS</I>, and Δ<I>tarMS</I> double mutant cells, were prepared from a laboratory and a community-associated methicillin-resistant <I>S. aureus</I> strain. Here, we describe the unexpected finding that β-GlcNAc WTA-deficient Δ<I>tarS</I> mutant cells (which have intact α-GlcNAc) escape from anti-WTA antibody-mediated opsonophagocytosis, whereas α-GlcNAc WTA-deficient Δ<I>tarM</I> mutant cells (which have intact β-GlcNAc) are efficiently engulfed by human leukocytes via anti-WTA IgG. Likewise, MBL binding in <I>S. aureus</I> cells was lost in the Δ<I>tarMS</I> double mutant but not in either single mutant. When we determined the serum concentrations of the anti-α- or anti-β-GlcNAc-specific WTA IgGs, anti-β-GlcNAc WTA-IgG was dominant in pooled human IgG fractions and in the intact sera of healthy adults and infants. These data demonstrate the importance of the WTA sugar conformation for human innate and adaptive immunity against <I>S. aureus</I> infection.</P>