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1
Content available Wave Propagation in a LRPC Composite Double Panel Structure with Periodically Attached Pillars and Etched Holes
Qian D.
Archives of Acoustics
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2018
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Vol. 43, No. 4
717--725
EN
The locally resonant phononic crystal (LRPC) composite double panel structure (DPS) made of a twodimensional periodic array of a two-component cylindrical LR pillar connected between the upper and lower composite plates is proposed. The plates are composed of two kinds of materials and periodically etched holes. In order to reveal the bandgap properties of structure theoretically, the band structures, displacement fields of eigenmodes and transmission power spectrums of corresponding 8 × 8 finite structure are calculated and displayed by using finite element method (FEM). Numerical results and further analysis demonstrate that if the excitation and response points are picked on different sides of the structure, a wide band gap with low starting frequency is opened, which can be treated as the coupling between dominant vibrations of pillars and plate modes. In addition, the influences of filled-in rubber, etched hole and viscidity of soft material on band gap are studied and understood with the help of “base-spring-mass” simplified model.
2
Content available Bandgap properties in locally resonant phononic crystal double panel structures with periodically attached pillars
Qian D., Shi Z.
Journal of Theoretical and Applied Mechanics
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2017
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Vol. 55 nr 4
1167--1179
EN
The locally resonant (LR) phononic crystal double panel structure made of a two-dimensional periodic array of a two-component cylindrical LR pillar connected between the upper and lower plates is proposed, and the bandgap properties of the structure are investigated theoretically in this paper. The band structures, displacement fields of eigenmodes and transmission power spectrums of the corresponding 8×8 finite structure are calculated by the finite element method. Numerical results and further analysis demonstrate that a band gap with a low starting frequency and a wide band width is opened by the coupling between dominant vibrations of the pillars and plate modes of the upper and lower plates when the vibration source and the receiver are considered on different sides of the structure. By comparing the band structures and displacement fields of the double panel and those of the single plate with the same parameters, many common characteristics are displayed. Then, the influence of geometrical parameters on the band gap are studied and understood with the help of a simple ‘spring-mass’ model.
3
Content available Using PWE/FE Method to Calculate the Band Structures of the Semi-Infinite PCs : Periodic in x-y Plane and Finite in z–direction
Qian D., Shi Z.
Archives of Acoustics
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2017
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Vol. 42, No. 4
735--742
EN
This paper introduces the concept of semi-infinite phononic crystal (PC) on account of the Infinite periodicity in x-y plane and finiteness in z-direction. The plane wave expansion and finite element methods are coupled and formulized to calculate the band structures of the proposed periodic elastic composite structures based on the typical geometric properties. First, the coupled plane wave expansion and finite element (PWE/FE) method is applied to calculate the band structures of the Pb/rubber, steel/epoxy and steel/aluminum semi-infinite PCs with cylindrical scatters. Then, it is used to calculate the band structure of the Pb/rubber semi-infinite PC with cubic scatter. Last, the band structure of the rubbercoated Pb/epoxy three-component semi-infinite PC is calculated by the proposed method. Besides, all the results are compared with those calculated by the finite element (FE) method implemented by adopting COMSOL Multiphysics. Numerical results and further analysis demonstrate that the proposed PWE/FE method has strong applicability and high accuracy.
4
Content available Design of simultaneous input-shaping-based SIRMs fuzzy control for double-pendulum-type overhead cranes
Qian D., Tong S., Yang B., Lee S.
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2015
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Vol. 63, nr 4
887--896
EN
Overhead cranes are extensively employed but their performance suffers from the natural sway of payloads. Sometime, the sway exhibits double-pendulum motions. To suppress the motions, this paper investigates the design of simultaneous input-shaping-based fuzzy control for double-pendulum-type overhead cranes. The fuzzy control method is based on the single input-rule modules (SIRMs). Provided the all the system variables are measurable, the SIRMs fuzzy controller is designed at first. To improve the performance of the fuzzy controller, the simultaneous input shaper is adopted to shape the control command generated by the fuzzy controller. Compared with other two control methods, i.e., the SIRMs fuzzy control and the convolved input-shaping-based SIRMs fuzzy control, simulation results illustrate the feasibility, validity and robustness of the presented control method for the anti-swing control problem of double-pendulum-type overhead cranes.
5
Content available remote Hierarchical sliding mode control for a class of SIMO under-actuated systems
Qian D., Yi J., Zhao D.
Control and Cybernetics
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2008
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Vol. 37, no 1
159-175
EN
A hierarchical sliding mode control approach is proposed for a class of SIMO under-actuated systems. This class of under-actuated systems is made up of several subsystems. Based on this physical structure, the hierarchical structure of the sliding surfaces is designed as follows. At first, the sliding surface of every subsystem is defined. Then the sliding surface of one subsystem is defined as the first layer sliding surface. The first layer sliding surface is used to construct the second layer sliding surface with the sliding surface of another subsystem. This process continues till the sliding surfaces of the entire subsystems are included. According to the hierarchical structure, the total control law is deduced by the Lyapunov theorem. In theory, the asymptotic stability of the entire system of sliding surfaces is proven and the parameter boundaries of the subsystem sliding surfaces are given. Simulation results show the feasibility of this control method through two typical SIMO under-actuated systems.
6
Content available remote Nitration of Toluene and Chlorobenzene with HNO3/Ac2O Catalyzed by Caprolactam-based Bronsted Acidic Ionic Liquids
Ql X., Cheng G., Lu Ch., Qian D.
Central European Journal of Energetic Materials
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2007
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Vol. 4, nr 3
105-113
EN
Several new caprolactam-based Bronsted acidic ionic liquids [Caprolactam]X (X- = pTSO-, BSO-, BF4-, NO3-) with relatively lower cost and lower toxicity were synthesized and for the first time used in catalyzing organic reaction. They showed good catalytic activity in the nitration of toluene and chlorobenzene with HNO3/Ac2O under mild conditions. Among them, [Caprolactam]pTSO was the best one probably because of its better affinity to aromatics than the others. [Caprolactam]pTSO catalyzed the nitration of toluene with achieving a high yield (99.7%, calculated by quantitative GC) and better para-selectivity (ortho/para=1.03) than the traditional mixed acid methodology. And the catalyst can be recycled for four times.
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