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Observer Design for A Class of Uncertain State-Delayed Nonlinear Systems
Junwei Lu,Chunmei Feng,Shengyuan Xu,Yuming Chu 대한전기학회 2006 International Journal of Control, Automation, and Vol.4 No.4
This paper deals with the observer design problem for a class of state-delayed nonlinear systems with or without time-varying norm-bounded parameter uncertainty. The nonlinearities under consideration are assumed to satisfy the global Lipschitz conditions and appear in both the state and measured output equations. The problem we address is the design of a nonlinear observer such that the resulting error system is globally asymptotically stable. For the case when there is no parameter uncertainty, a sufficient condition for the solvability of this problem is derived in terms of linear matrix inequalities and the explicit formula of a desired observer is given. Based on this, the robust observer design problem for the case when parameter uncertainties appear is considered and the solvability condition is also given. Both of the solvability conditions obtained in this paper are delay-dependent. A numerical example is provided to demonstrate the applicability of the proposed approach.
Xiaoling Che,Chunmei Yang,Liping Pan,Didi Gu,Guidong Dai,Jian Shu,Lu Yang 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00
Background Non-intrusive imaging of gastrointestinal (GI) tract using computed tomography (CT) contrast agents is of the most significant issues in the diagnosis and treatment of GI diseases. Moreover, spectral CT, which can generate monochromatic images to display the X-ray attenuation characteristics of contrast agents, provides a better imaging sensitivity for diagnose inflammatory bowel disease (IBD) than convention CT imaging. Methods Herein, a convenient and one-pot synthesis method is provided for the fabrication of small-molecule lanthanide complex Holmium-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (Ho-DOTA) as a biosafe and high-performance spectral CT contrast agent for GI imaging with IBD. In vivo CT imaging was administered with both healthy mice and colitis mice induced by dextran sodium sulfate. Results We found that Ho-DOTA accumulated in inflammation sites of large intestines and produced high CT contrast compared with healthy mice. Both in vitro and in vivo experimental results also showed that Ho-DOTA provided much more diagnostic sensitivity and accuracy due to the excellent X-ray attenuation characteristics of Ho- DOTA compared with clinical iodinate agent. Furthermore, the proposed contrast media could be timely excreted from the body via the urinary and digestive system, keeping away from the potential side effects due to long-term retention in vivo. Conclusion Accordingly, Ho-DOTA with excellent biocompatibility can be useful as a potential high-performance spectral CT contrast agent for further clinical imaging of gastrointestinal tract and diagnosis of intestinal system diseases.
NH3-SCR performance and characterization over magnetic iron-magnesium mixed oxide catalysts
Liting Xu,Shengli Niu,Chunmei Lu,Dong Wang,Kang Zhang,Jing Li 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.5
A series of magnetic iron-magnesium mixed oxide catalysts (Fe1−xMgxOz) were synthesized via a novel coprecipitation method with microwave thermal treatment, and their activity in NH3-SCR was tested on a quartz fixedbed reactor. Physical and chemical properties of the catalysts were characterized by X-ray diffraction (XRD), N2- adsorption-desorption, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Fe0.8Mg0.2Oz with excellent N2 selectivity and resistance to SO2 and H2O was validated as the proper SCR catalyst, with the maximum NOx conversion of 99.1% fulfilled at 325 oC. Activity was strongly influenced by the γ-Fe2O3 crystalline phase, and magnesium existed in an amorphous phase and interacted with iron oxide intensively to form solid solution in favor of SCR. For Fe0.8Mg0.2Oz catalyst, optimum pore diameter distribution, appropriate surface area, pore volume and abundant lattice oxygen on the surface could be guaranteed, which is good for the diffusion process and enhances the activity.
Liting Xu,Shengli Niu,Dong Wang,Chunmei Lu,Qi Zhang,Kang Zhang,Jing Li 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.63 No.-
A series of titanium modified FexMgyOz catalysts were prepared by coprecipitation method and impregnation-coprecipitation method with microwave assistant and their catalytic capability in selective catalytic reduction (SCR) was evaluated. Appropriate amount of either titanium or TiO2 could both improve the catalytic performance of FexMgyOz catalyst, especially above 350 °C. 7.5%Ti–FexMgyOz catalyst with wide temperature range of 225–400 °C could achieve the maximum NOx conversion of 100%, while FexMgyOz/TiO2(b) catalyst exhibited the best catalytic performance in the present of H2O and SO2. Characterization results exhibited that γ-Fe2O3 was the main active phase, TiO2 was mainly in the form of anatase TiO2 and both titanium and magnesium existed in amorphous phase. The crystalline grain could be refined with the addition of either titanium or TiO2, as well as the increase of BET surface area and pore volume. The acid sites, redox ability and the chemisorbed oxygen were the most important factors in SCR reaction. The introduction of titanium and TiO2 had the effect of increasing the strength of the acid sites, which could attribute to the improvement of catalytic performance over titanium modified FexMgyOz catalysts.
Xiaoyu Li,Juan Chen,Shouyan Chen,Chunmei Lu,Guangqian Luo,Hong Yao 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.101 No.-
Impact of arsenic on the performance of Mg-Ti modified iron-based catalyst during selective catalyticreduction of NOx with ammonia was studied. The results indicated that Mg and Ti modification not onlyimproved the catalytic activity at 100–350 C, but also exhibited remarkable anti-arsenic ability. Mg wasdominant in the excellent anti-arsenic performance, and this role was firstly recognized. The anti-arsenicmechanism of Mg-Ti modified iron-based catalyst was ascribed to two aspects. One side, Mg exhibitedwell reactivity with arsenic which competed with Fe for the adsorption of arsenic and protected activeiron sites from arsenic occupation. The other side, presence of Mg promoted the formation of MgFe2O4in view of the strong interactions between Mg and Fe, suppressing the interactions between arsenicand Fe. Instead, gaseous arsenic turned to bond with Mg-O sites. Consequently, surface acid sites andfunction Fe-OH/ Fe = O bonds were preserved for de-NOx. Moreover, increase of oxygen content and temperatureweakened the deactivation of Mg-Ti modified iron-based catalyst by arsenic. It was due to theoxidation of As2O3 with oxygen content increase and the strengthened reactivity of non-active iron siteswith arsenic and Mg with arsenic as temperature elevation, inhibiting the interactions between activeiron sites with arsenic.
Iron-manganese-magnesium mixed oxides catalysts for selective catalytic reduction of NOx with NH3
Kang Zhang,Liting Xu,Shengli Niu,Chunmei Lu,Dong Wang,Qi Zhang,Jing Li 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.6
SCR activity at low temperature over iron oxide catalyst was prominently optimized by adding manganese and magnesium. Fe0.7Mn0.15Mg0.15Oz(n(Mn)/[n(Fe)+n(Mn)+n(Mg)])=0.15 and n(Mg)/[n(Fe)+n(Mn)+n(Mg)]=0.15) presented better performance in the low temperature SCR and NOx conversion of 90% could be achieved over 125 oC. Meanwhile, part of manganese and magnesium oxides were highly dispersed on the catalyst surface in an amorphous phase to react with iron oxide to form solid solution. Manganese and magnesium dopants could optimize the pore structure and distribution of γ-Fe2O3 to enhance the surface area and pore volume. Moreover, O2 participated in SCR reaction at a faster rate than NH3. In addition, the effect of SO2 was proved to be irreversible, whereas the inhibition of H2O could be rapidly removed after its removal.
Tang Xincheng,Niu Shengli,Zhao Shuang,Zhang Xiangyu,Li Ximing,Yu Hewei,Lu Chunmei,Han Kuihua 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.77 No.-
The carbon-based heterogeneous acid catalyst is synthesized from bituminous coal through the partialcarbonization and sulfonation method and applied to catalyze the esterification of oleic acid withmethanol for biodiesel production. Various characterization methods are used to explain catalyticfeatures and molecular simulation is conducted to analyze the promoted mechanism of acid catalyst inesterification. Carbon catalyst, prepared by partially carbonized at 350 C and sulfonated at 105 C,catalyzes esterification with biodiesel yield of 98.70%. Transition state analysis implies that acid catalystreduces the activation energy through providing proton to promote esterification.