Robust Discrete-time Control for Uncertain time-delay Systems with Nonlinearities Under Hölder Continuity

Xin Wang,Xin Zuo,Jianwei Liu,Huaqing Liang,Qi Pan 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10

This paper is concerned with the robust discrete-time control for uncertain time-delay systems with nonlinearities and external noises. The parameter uncertainties enter into all the system matrices. The time-varying delay is unknown with given lower and upper bounds. The stochastic nonlinearities are described by satisfying a class of α Hölder condition. The problem addressed is the analysis and design of a stable controller such that, for all the parameter uncertainties, time-delay, stochastic nonlinearities and external noises, the resulting closed-loop system is exponentially stabile. The controller gain can be got by linear matrix inequalities (LMIs). Numerical examples are given to illustrate the effectiveness and verify the proposed theoretical results.

Damage detection of nonlinear structures with analytical mode decomposition and Hilbert transform

Zuo-Cai Wang,Dong Geng,Wei-Xin Ren,Guang-Feng Zhang,Gen-Da Chen 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.15 No.1

This paper proposes an analytical mode decomposition (AMD) and Hilbert transform method for structural nonlinearity quantification and damage detection under earthquake loads. The measured structural response is first decomposed into several intrinsic mode functions (IMF) using the proposed AMD method. Each IMF is an amplitude modulated-frequency modulated signal with narrow frequency bandwidth. Then, the instantaneous frequencies of the decomposed IMF can be defined with Hilbert transform. However, for a nonlinear structure, the defined instantaneous frequencies from the decomposed IMF are not equal to the instantaneous frequencies of the structure itself. The theoretical derivation in this paper indicates that the instantaneous frequency of the decomposed measured response includes a slowly-varying part which represents the instantaneous frequency of the structure and rapidly-varying part for a nonlinear structure subjected to earthquake excitations. To eliminate the rapidly-varying part effects, the instantaneous frequency is integrated over time duration. Then the degree of nonlinearity index, which represents the damage severity of structure, is defined based on the integrated instantaneous frequency in this paper. A one-story hysteretic nonlinear structure with various earthquake excitations are simulated as numerical examples and the degree of nonlinearity index is obtained. Finally, the degree of nonlinearity index is estimated from the experimental data of a seven-story building under four earthquake excitations. The index values for the building subjected to a low intensity earthquake excitation, two medium intensity earthquake excitations, and a large intensity earthquake excitation are calculated as 12.8%, 23.0%, 23.2%, and 39.5%, respectively.

Adsorption of Villin Headpiece onto Graphene, Carbon Nanotube, and C60: Effect of Contacting Surface Curvatures on Binding Affinity

Zuo, Guanghong,Zhou, Xin,Huang, Qing,Fang, Haiping,Zhou, Ruhong American Chemical Society 2011 The Journal of Physical Chemistry Part C Vol.115 No.47

<P>The adsorption of protein villin headpiece (HP35) onto a graphene has been investigated using large scale molecular dynamics simulations, and the results are compared with similar adsorptions onto a single-wall carbon nanotube and a fullerene, C60. It is found that HP35 loses most of its native secondary and tertiary structures after the adsorption onto graphene. The π–π stacking interactions between the graphene and HP35’s aromatic residues play a key role in this adsorption. The graphene’s softness also helps the binding by adapting its own shape to fit better with aromatic residues in forming stronger π–π stacking interactions. Interestingly, the mechanism of HP35 adsorption onto the other two graphitic nanomaterials is found to be somewhat different, in which the π–π stacking interactions play a lesser role than the dispersion interactions between the nanomaterial and HP35’s aliphatic side chains. These findings indicate that in addition to the chemical composition, the shape of the nanoparticle is also an important factor in determining its interaction with proteins: the contacting surface curvature can lead to different adsorption mechanisms.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2011/jpccck.2011.115.issue-47/jp208967t/production/images/medium/jp-2011-08967t_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp208967t'>ACS Electronic Supporting Info</A></P>

A data fusion method for bridge displacement reconstruction based on LSTM networks

Zuo-Cai Wang,Da-You Duan,Xiao-Tong Sun,Yu Xin 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.29 No.4

Bridge displacement contains vital information for bridge condition and performance. Due to the limits of direct displacement measurement methods, the indirect displacement reconstruction methods based on the strain or acceleration data are also developed in engineering applications. There are still some deficiencies of the displacement reconstruction methods based on strain or acceleration in practice. This paper proposed a novel method based on long short-term memory (LSTM) networks to reconstruct the bridge dynamic displacements with the strain and acceleration data source. The LSTM networks with three hidden layers are utilized to map the relationships between the measured responses and the bridge displacement. To achieve the data fusion, the input strain and acceleration data need to be preprocessed by normalization and then the corresponding dynamic displacement responses can be reconstructed by the LSTM networks. In the numerical simulation, the errors of the displacement reconstruction are below 9% for different load cases, and the proposed method is robust when the input strain and acceleration data contains additive noise. The hyper-parameter effect is analyzed and the displacement reconstruction accuracies of different machine learning methods are compared. For experimental verification, the errors are below 6% for the simply supported beam and continuous beam cases. Both the numerical and experimental results indicate that the proposed data fusion method can accurately reconstruct the displacement.

Effects of Different Colored Light-quality Selective Plastic Films on Growth, Photosynthetic Abilities, and Fruit Qualities of Strawberry

Xin Peng,Bin Wang,Xile Wang,Binbin Ni,Zhaojiang Zuo 한국원예학회 2020 원예과학기술지 Vol.38 No.4

Light quality regulates plant growth and photosynthesis, the drivers of fruit quality, and light quality can be controlled by colored light-quality selective plastic films in field production. To identify the optimal color of plastic film for high-quality strawberry (Fragaria × ananassa) fruit production, plant growth, photosynthetic abilities, and fruit qualities were investigated under transparent (T), red (R), yellow (Y), green (G), blue (B), and purple (P) films. The R film showed the maximum promoting effects on leaf area, petiole length, leaf biomass, and shoot biomass. The R film improved photosynthetic abilities by increasing photosynthetic pigment content, quantum yield (φPo), electron transfer (Ψo and φEo), the density of reaction centers (RC/CSm), and the photosynthetic performance index (PIabs), and by decreasing the dissipation of absorbed solar energy as heat (φDo), while varied reverse effects were detected under other films. For fruit qualities, the R film also improved fruit weight and the content of total sugar, anthocyanin, and soluble protein. Therefore, the R light-quality selective plastic film should be suitable for strawberry production due to the promoting effects on plant growth, photosynthetic abilities, and fruit weight and quality.

Nonlinear boundary parameter identification of bridges based on temperature-induced strains

Zuo-Cai Wang,Guo-Peng Zha,Wei-Xin Ren,Ke Hu,Hao Yang 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.5

Temperature-induced responses, such as strains and displacements, are related to the boundary conditions. Therefore, it is required to determine the boundary conditions to establish a reliable bridge model for temperature-induced responses analysis. Particularly, bridge bearings usually present nonlinear behavior with an increase in load, and the nonlinear boundary conditions cause significant effect on temperature-induced responses. In this paper, the bridge nonlinear boundary conditions were simulated as bilinear translational or rotational springs, and the boundary parameters of the bilinear springs were identified based on the measured temperature-induced responses. First of all, the temperature-induced responses of a simply support beam with nonlinear translational and rotational springs subjected to various temperature loads were analyzed. The simulated temperature-induced strains and displacements were assumed as measured data. To identify the nonlinear translational and rotational boundary parameters of the bridge, the objective function based on the temperature-induced responses is then created, and the nonlinear boundary parameters were further identified by using the nonlinear least squares optimization algorithm. Then, a beam structure with nonlinear translational and rotational springs was simulated as a numerical example, and the nonlinear boundary parameters were identified based on the proposed method. The numerical results show that the proposed method can effectively identify the parameters of the nonlinear boundary conditions. Finally, the boundary parameters of a real arch bridge were identified based on the measured strain data and the proposed method. Since the bearings of the real bridge do not perform nonlinear behavior, only the linear boundary parameters of the bridge model were identified. Based on the bridge model and the identified boundary conditions, the temperature-induced strains were recalculated to compare with the measured strain data. The recalculated temperature-induced strains are in a good agreement with the real measured data.

Organic Montmorillonite/Polyethersulfone/Polytetrafluoroethylene Ternary Nanocomposites: Characterization and Tribological Performance in Dry Sliding Condition

Zhen Zuo,Yulin Yang,Pengtao Yan,Laizhou Song,Xin Jin 한국섬유공학회 2022 Fibers and polymers Vol.23 No.6

Polyethersulfone (PES)/polytetrafluoroethylene (PTFE) based composite were prepared with the nanofiller oforganic montmorillonite (OMMT). Compared with original OMMT, the interlayer spacing of OMMT in nanocomposites wasdecreased from 3.47 nm to 1.35 nm, attributing to the decomposition of interlayer quaternary ammonium salt. OMMTnanofiller was favorable to improve the thermal stability and abrasion resistance of PES/PTFE compounds. The preferablewear property of OMMT/PES/PTFE composite was mainly ascribed to the load bearing capacity of OMMT on the wornsurface of polymer composites. The OMMT/PES/PTFE compound with 10 wt% OMMT exhibited the lowest wear rate,owing to its densification morphology. Because of the absence of PTFE transfer film, the friction coefficient of OMMT/PES/PTFE compound with 10 wt% OMMT were higher than those of PTFE and PES/PTFE compounds.

Damage detection of nonlinear structures with analytical mode decomposition and Hilbert transform

Wang, Zuo-Cai,Geng, Dong,Ren, Wei-Xin,Chen, Gen-Da,Zhang, Guang-Feng Techno-Press 2015 Smart Structures and Systems, An International Jou Vol.15 No.1

This paper proposes an analytical mode decomposition (AMD) and Hilbert transform method for structural nonlinearity quantification and damage detection under earthquake loads. The measured structural response is first decomposed into several intrinsic mode functions (IMF) using the proposed AMD method. Each IMF is an amplitude modulated-frequency modulated signal with narrow frequency bandwidth. Then, the instantaneous frequencies of the decomposed IMF can be defined with Hilbert transform. However, for a nonlinear structure, the defined instantaneous frequencies from the decomposed IMF are not equal to the instantaneous frequencies of the structure itself. The theoretical derivation in this paper indicates that the instantaneous frequency of the decomposed measured response includes a slowly-varying part which represents the instantaneous frequency of the structure and rapidly-varying part for a nonlinear structure subjected to earthquake excitations. To eliminate the rapidly-varying part effects, the instantaneous frequency is integrated over time duration. Then the degree of nonlinearity index, which represents the damage severity of structure, is defined based on the integrated instantaneous frequency in this paper. A one-story hysteretic nonlinear structure with various earthquake excitations are simulated as numerical examples and the degree of nonlinearity index is obtained. Finally, the degree of nonlinearity index is estimated from the experimental data of a seven-story building under four earthquake excitations. The index values for the building subjected to a low intensity earthquake excitation, two medium intensity earthquake excitations, and a large intensity earthquake excitation are calculated as 12.8%, 23.0%, 23.2%, and 39.5%, respectively.

Selective oxidation of 5-formyloxymethylfurfural to 2, 5-furandicarboxylic acid with Ru/C in water solution

Zhihao Si,Xin Zhang,Miao Zuo,Tao Wang,Yong Sun,Xing Tang,Xianhai Zeng,Lu Lin 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.2

2, 5-furandicarboxylic acid (FDCA) is a one of the most promising biomass-derived chemicals to substitute the non-renewable terephthalic acid as the monomer for producing polyethyleneterephthalate. At present, the oxidation of HMF is regarded as a prevalent way to prepare FDCA. Nevertheless, the isolation and storage of HMF is still a challenge. Herein, based on the higher stability of 5-formyloxymethylfurfural (FMF) than 5-hydroxymethylfurfural (HMF), we present an effective preparation route to prepare FDCA by substituting HMF with FMF as feedstock. A complete conversion of FMF and a 93.55% selectivity of FDCA were obtained in the mixed solvent of water and 1, 2- dioxane using Ru/C as catalyst and O2 as oxidant. An improved process was developed for preparing FDCA using FMF as feedstock. The investigation of conversion pathway showed that FMF and HMF were simultaneously oxidized to 2, 5-diformylfuran (DFF) in a case of the existence of the reversible equilibrium between FMF and HMF. Then DFF was oxidized to 5-formyl-2-furancarboxylic acid (FFCA). Subsequently, FFCA was oxidized to FDCA. In this process, the oxidation of FFCA to FDCA was determined as the rate-determining step. Furthermore, appropriate alkalinity favored the selectivity of FDCA and the conversion of FMF.

Output-Feedback Control of a Class of Stochastic Nonlinear Systems with Power Growth Conditions

Long-Chuan Guo,Xin Zuo,Hua-Qing Liang,Jian-Wei Liu 제어·로봇·시스템학회 2014 International Journal of Control, Automation, and Vol.12 No.2

This paper investigates the problem of output-feedback stabilization for a class of stochastic nonlinear systems in which the nonlinear terms depend on unmeasurable states besides measurable input. We extend linear growth conditions to power growth conditions and reduce the control effort. By using backstepping technique, choosing a high-gain parameter, an output-feedback controller is designed to ensure the closed-loop system globally asymptotically stable in probability. The efficiency of the output-feedback controller is demonstrated by a simulation example.