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Nonlinear Forced Vibration of Cantilevered Pipes Conveying Fluid

Acta Mechanica Solida Sinica 2018年第1期31卷 32-50页

作者： zhi-Yuan liu Lin Wang Xi-Ping Sun Department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment Wuhan 430074 China Tianjin Research Institute Water Transport Engineering M.O.T. Test Detection Center of Water Transport Engineering Tianjin 300356 China

The nonlinear forced vibrations of a cantilevered pipe conveying fluid under base excitations are explored by means of the full nonlinear equation of motion, and the fourth- order Runge-Kutta integration algorithm is used as a numerical tool to solve the discretized equations. The self-excited vibration is briefly discussed first, focusing on the effect of flow velocity on the stability and post-flutter dynamical behavior of the pipe system with parameters close to those in previous experiments. Then, the nonlinear forced vibrations are examined using several concrete examples by means of frequency response diagrams and phase-plane plots. It shows that, at low flow velocity, the resonant amplitude near the first-mode natural frequency is larger than its counterpart near the second-mode natural frequency. The second-mode frequency response curve clearly displays a softening-type behavior with hysteresis phenomenon, while the first-mode frequency response curve almost maintains its neutrality. At moderate flow velocity, interestingly, the first-mode resonance response diminishes and the hysteresis phenomenon of the second-mode response disappears. At high flow velocity beyond the flutter threshold, the frequency response curve would exhibit a quenching-like behavior. When the excitation frequency is increased through the quenching point, the response of the pipe may shift from quasiperiodic to periodic. The results obtained in the present work highlight the dramatic influence of internal fluid flow on the nonlinear forced vibrations of slender Pipes.

关键词： Pipe conveying fluid Base excitation Nonlinear dynamics Primary resonance,Superharmonie resonance Forced vibration

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Robust Control Strategy for the Speed Control of Brushless DC Motor

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Journal of Harbin Institute of Technology(New Series) 2013年第2期20卷 90-94页

作者： zhi liu Bai-Fen liu School of Traffic and Transportation Engineering Central South University School of Electrical and Electronic Engineering East China Jiaotong University

Brushless DC motor ( BLDCM) speed servo system is multivariable,nonlinear and strong coupling. The parameter variation, the cogging torque and the load disturbance easily influence its performance. Therefore,it is difficult to achieve superior performance by using the conventional PID controller. To solve the deficiency,the paper represents the algorithm of active-disturbance rejection control ( ADRC) based on back-propagation ( BP) neural network. The ADRC is independent on accurate system and its extended-state observer can estimate the disturbance of the system accurately. However,the parameters of Nonlinear Feedback ( NF) in ADRC are difficult to obtain. So in this paper,these parameters are self-turned by the BP neural network. The simulation and experiment results indicate that the ADRC based on BP neural network can improve the performances of the servo system in rapidity,control accuracy,adaptability and robustness.

关键词： brushless DC motor ( BLDCM) BP ( back propagation algorithms) ADRC ( active-disturbance rejection control) parameters self-turning.

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Cognitive Study of the Linear Order of the English Construction“X and Y”

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Journal of Electronic Science and Technology 2017年第1期15卷 20-24页

作者： Yong-zhi liu Fan Fan College of Foreign Languages&Cultures Chengdu University of TechnoiogyChengdu 610059China

The English construction “X and Y ”refers to the coordination of two words with and as conjunction, X and Y being of the same part of speech and parallel meanings. This paper is a cognitive study of the linear order of the English construction “X and Y ”from the perspectives of cognitive salience, cognitive iconicity, and cognition of formal rules. The linear characteristics of “X and Y ” are revealed as follows： 1）salience-downgrading order; 2） chronological iconicity;3） cognition of alphabetic order and prosodic order.

关键词： cognition conjunction syntactic linguistics salient formal bread X and Y discussion father

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Solutions of multiple vector refinement equations with infinite mask

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Applied Mathematics(A Journal of Chinese Universities) 2009年第2期24卷 209-213页

作者： LI Na liu zhi-song Department of Mathematics Shandong Institute of Education Jinan 250013 China Information College Zhejiang Ocean University Zhoushan 316004 China

This paper is devoted to investigating the solutions of refinement equations of the form Ф（x）=∑α∈Z^s α（α）Ф（Mx-α）,x∈R^s,where the vector of functions Ф = （Ф1,… ,Фr）^T is in （L1（R^s））^r, α =（α（α））α∈Z^s is an infinitely supported sequence of r × r matrices called the refinement mask, and M is an s × s integer matrix such that lim n→∞ M^-n =0, with m = detM. Some properties about the solutions of refinement equations axe obtained.

关键词： refinement equation refinement mask multiple refinable function

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Electrochemical reactions at the electrode/solution interface:Theory and applications to water electrolysis and oxygen reduction

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Science China Chemistry 2010年第3期53卷 542-551页

作者： Fang, Ya Hui liu, zhi Pan Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Department of Chemistry Fudan University Shanghai 200433 China

Theoretical simulations on complex electrochemical processes have been developed on the basis of the understanding in electrochemistry,which has benefited from quantum mechanics *** article reviews the recent progress on the theory and applications in *** representative reactions,namely water electrolysis and oxygen reduction,are selected to illustrate how the theoretical methods are applied to electrocatalytic *** microscopic nature of these electrochemical reactions under the applied potentials is described and the understanding of the reactions is *** thermodynamics and kinetics of the electrochemical reactions affected by the interplay of the electrochemical potential,the bonding strength and the local surface structure are addressed at the atomic level.

关键词： density functional theory electrode/solution interface water electrolysis oxygen reduction reaction review

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Towards precise reconstruction of gene regulatory networks by data integration

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Frontiers of Electrical and Electronic Engineering in China 2018年第2期6卷 113-128页

作者： zhi-Ping liu Department of Biomedical Engineering School of Control Science and Engineering Shandong University Jinan 250061 China

Background： More and more high-throughput datasets are available from multiple levels of measuring gene regulations. The reverse engineering of gene regulatory networks from these data offers a valuable research paradigm to decipher regulatory mechanisms. So far, numerous methods have been developed for reconstructing gene regulatory networks. Results： In this paper, we provide a review of bioinformatics methods for inferring gene regulatory network from omics data. To achieve the precision reconstruction of gene regulatory networks, an intuitive alternative is to integrate these available resources in a rational framework. We also provide computational perspectives in the endeavors of inferring gene regulatory networks from heterogeneous data. We highlight the importance of multi-omics data integration with prior knowledge in gene regulatory network inferences. Conclusions： We provide computational perspectives of inferring gene regulatory networks from multiple omics data and present theoretical analyses of existing challenges and possible solutions. We emphasize on prior knowledge and data integration in network inferences owing to their abilities of identifying regulatory causality.

关键词： gene regulatory network computational inference data integration bioinformatics

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Correlation between Primary and Secondary Recrystallization Texture Components in Low-temperature Reheated Grain-oriented Silicon Steel

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Journal of Iron and Steel Research International 2016年第11期23卷 1234-1242页

作者： Gong-tao liu zhi-qiao liu Ping YANG Wei-min MAO School of Materials Science and Engineering University of Science and Technology Beijing

Low-temperature slab-reheated grain-oriented silicon steel is characterized by a sharp {411}〈148〉 primary recrystallization texture. To date, the influence of this texture on secondary recrystallization is not clear. Microtextures in primary and secondary reerystallized sheets of low-temperature reheated grain-oriented silicon steel were examined using electron backscatter diffraction. By comparing the textures and microstructures of specific primary reerystallized grains neighboring secondary grains with those of other primary grains, the influences of primary re- crystallization textures and microstructures on the orientations of secondary grains were investigated. Results show that for low-temperature reheated graiworiented silicon steel, the primary recrystallization sheet comprises { 411 } 〈148〉, {111}〈112〉, and {001}〈120〉 texture componems. During secondary recrystallization, the {111}〈112〉 primary recrystallized grains were easily consumed by abnormally grown Goss, deviated Goss, Brass, or {210}〈001〉grains ;the { 411 }〈148〉 primary recrystallized grains were more resistant to being swallowed; and the {001} 〈120 grains were the most resistant to being consumed. For a particular primary grain, the distribution of its surrounding grain boundaries determined how easily it is consumed during secondary recrystallization. Primary grains surrounded by 20°- 45° grain boundaries were consumed much earlier than those having grain boundaries above 45°, which is in accordance with high-energy grain boundary theory. In addition, special ∑9 boundaries between {411}〈148〉 and Goss grains move more slowly than ∑9 boundaries between {111 }〈112〉 and Goss grains, which is attributed to the different positions of 〈110〉 rotation axis with respect to the normals of grain boundaries.

关键词： grain-oriented silicon steel secondary recrystallization texture low-temperature slab reheating

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Novel method for the determination of five carbamate pesticides in water samples by dispersive liquid-liquid microextraction combined with high performance liquid chromatography

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Chinese Chemical Letters 2009年第2期20卷 213-216页

作者： zhi Mei liu Xiao Huan Zang Wei Hua liu Chun Wang zhi Wang Key Laboratory of Bioinorganic Chemistry College of Sciences Agricultural University of Hebei Baoding 071001 China

A novel method for the determination of five carbamate pesticides （metolcarb, carbofuran, carbaryl, isoprocard and diethofencard） in water samples was developed by dispersive liquid-liquid microextraction （DLLME） coupled with high performance liquid chromatography-diode array detector （HPLC-DAD）. Some experimental parameters that influence the extraction efficiency were studied and optimized to obtain the best extraction results. Under the optimum conditions for the method, the calibration curve was linear in the concentration range from 5 to 1000 ng mL^-1 for all the five carbamate pesticides, with the correlation coefficients （r^2） varying from 0.9984 to 0.9994. Good enrichment factors were achieved ranging from 80 to 177- fold, depending on the compound. The limits of detection （LODs）（S/N = 3） were ranged from 0.1 to 0.5 ng mL^-1. The method has been successfully applied to the analysis of the pesticide residues in environmental water samples.

关键词： Carbamate pesticides High performance liquid chromatography Diode array detection Dispersive liquid-liquid microextraction Water samples

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Synthesis, characterization, and property test of crystalline polyferric sulfate adsorbent used in treatment of contaminated water with a high As(Ⅲ) content

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International Journal of Minerals,Metallurgy and Materials 2018年第10期25卷 1217-1225页

作者： Ping-chao Ke zhi-hong liu Lin Li School of Metallurgy and Environment Central South UniversityChangsha 410083China The Robert M.Buchan Department of Mining Queen's UniversityKingstonON K7L 3N6Canada

A crystalline polyferric sulfate(PFS) adsorbent was synthesized by oxidizing and precipitating ferrous ions in air atmospheric conditions. The morphology, structure, specific surface area(SSA), and adsorptive efficacy of the adsorbent to As(Ⅲ) were characterized by scanning electron microscope(SEM) and transmission electron microscopy(TEM) images, X-ray diffraction(XRD) patterns, Fourier-transform infrared(FTIR) spectra, BET SSA analyses, and adsorption experiments. The adsorbent showed a near-spherical aggregate structure and had good crystallinity. A significant amount of α-goethite co-precipitated with PFS in the case of the initial ferrous concentration of 1 mol/L and increased SSA of the adsorbent. The stability region of ferric compounds in the process was drawn and applied to analyze the iron behavior during the synthesis. The adsorption of As(Ⅲ) in high As(Ⅲ)-containing solutions fitted the Langmuir isotherm model adequately. The absorbent with co-precipitation of α-goethite showed good adsorbability for As(Ⅲ) and good filtering performance in the high As(Ⅲ)-containing solution of 10–100 mg/L under acidic, neutral, and alkaline conditions(pH 2.09–9.01). After the adsorption process, the stability of the residues bearing As(Ⅲ) was evaluated by toxic characteristic leaching procedure(TCLP) tests. The results indicated that the residues were extremely stable, and the concentrations of arsenic in the leaching solutions were less than 0.01 mg/L.

关键词： polyferric sulfate crystal structure α-goethite high As(Ⅲ)-containing contaminated water wide pH range As(Ⅲ) adsorption

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Microstructure,mechanical properties and post-weld heat treatments of dissimilar laser-welded Ti_(2)AlNb/Ti60 sheet

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Rare Metals 2023年第4期42卷 1332-1342页

作者： Yong Wu Gang liu zhi-Qiang liu Ze-Jun Tang Bin Wang State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin150001China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin150001China College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing211106China Beijing Xinghang Mechanical-Electrical Equipment Co. Ltd.Beijing100074China

Dissimilar joining of Ti_(2)AlNb and Ti60 rolled sheet was performed by laser beam *** microstructures and mechanical properties of as-welded and post-weld heat-treated Ti_(2)AlNb/Ti60 joints were investigated by microstructure observation and mechanical properties *** fusion zone(FZ)of the as-welded joint consisted of B_(2)/βmatrix and small S2 *** heataffected zones HAZ-Ti_(2)AINb and HAZ-Ti60 for the aswelded joint were characterized asα_(2)+B_(2)/β+O andα'+α+β+S_(2),*** tensile strength and elongation of as-welded sheet were 597.5 MPa and 6.2%at650℃,*** of the plastic deformation was taken place at the side of Ti60 *** the increase in the heat treatment temperature,the anchoring strength between each other of B_(2)/βgrains was enhanced by the precipitated lamellarα'and O grains at the *** depth of the fracture dimples increased with the heat treat temperature *** heat-treated welding joint at970℃presented a good balance of the tensile strength and plasticity,where the tensile strength and the elongation were enhanced to 669.7 MPa and 7.1%at 650℃,respectively.

关键词： Ti_(2)AlNb Laser beam welding Post-weld heat treatment Mechanical properties Dissimilar welding

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