Qian Chen

Nanjing University, Nanjing, Jiangsu Sheng, China

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Publications (4)5.85 Total impact

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    ABSTRACT: We theoretically study the band structures of Lamb waves in one-dimensional phononic crystal plates consisting of piezoelectric ceramics placed periodically in epoxy with epoxy or piezoelectric ceramic substrate by the virtual plane wave expansion method. The dependences of the widths and starting frequencies of first band gaps (FBG) on the substrate's thickness, the filling fraction, and the lattice spacing are calculated for different materials of substrate under different electric boundary conditions, i.e., short circuit (SC) and open circuit (OC). The FBG width decreases gradually as the substrate's thickness increases and the FBG starting frequency increases progressively as the thickness increases on the whole. The FBG widths and starting frequencies with SC are always larger than with OC. Our research shows that it is possible to control the width and starting frequency of the FBG in the engineering according to need by choosing suitable values of the substrate's thickness, the filling fraction, and the lattice spacing.
    IEEE transactions on ultrasonics, ferroelectrics, and frequency control 03/2009; 56(2):361-7. · 1.80 Impact Factor
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    ABSTRACT: It has been found experimentally that application of sub-mega and low megahertz ultrasound (US) of spatial and temporal averaged intensity /(sata) up to 10 W/cm(2) during the process of preparing pathological sections of the mouse tissue has shortened the processing time from 12h (without US) to less than half an hour (with US). The experiment has also showed that the processing time reached the shortest for ultrasound f=200 kHz among the frequencies of 200 kHz, 400 kHz, 600 kHz, 800 kHz and 1 MHz used in this study. It has been proposed that ultrasound inducing non-inertial cavitation enhanced the permeability of cell membrane to liquid. Thus tissue fixation and dehydration were speeded up by application of US.
    Ultrasonics 01/2008; 47(1-4):78-81. · 2.03 Impact Factor
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    ABSTRACT: Theoretical studies are presented for the band structures of bulk waves in a two-dimensional composite structure consisting of rectangular piezoelectric ceramics placed periodically in an epoxy substrate. The dependences of the widths and starting frequencies of the first bandgaps (FBGs) on the filling fraction and the ratio of length to width of the embedded section are calculated for different polarized directions of the piezoelectric ceramics and different phononic structures. Our research shows that the FBG depend strongly on the polarized directions, the phononic structures, the filling fraction and the ratio of length to width, respectively. Therefore, one can control the FBG in engineering according to need by choosing these parameters of the system.
    Smart Materials and Structures 11/2007; 17(1):015008. · 2.02 Impact Factor
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    ABSTRACT: We have proposed a multi-layer structure for concealing an electromagnetic sensing system (a sensor is inserted into a scatterer), using isotropic single-negative materials whose material parameters are completely independent of those of the host matrix and the concealed system. The numerical results show that only three kinds of different isotropic homogeneous materials are sufficient to yield the cloaking effect even in the presence of weak loss. This may significantly facilitate the experimental realization of a well-performed sensor-cloaking device.