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Enhanced scattering of acoustic waves at interfaces

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Frontiers of physics 2012年第3期7卷 319-323页

作者： Li Zhao Bin Liu Yin-hao Gao Yan-jiao Zhao Ji-ping Huang Department of Physics and State Key Laboratory of Surface Physics Fudan UniversityShanghai 200433China School of Machinery and Electricity Henan Institute of Science and TechnologyXinxiang 453003China Advanced Materials Laboratory Fudan UniversityShanghai 200438China

We propose a general method to realize a total scattering of an incident acoustic wave at interfaces between different media while allowing the flow of air, fluids and/or particles. This originates from the enlargement of the equivalent acoustic scattering cross section of an embedded object coated with acoustic metamaterials, which causes the coated object to behave as a scatterer bigger than its physical size. We theoretically design a model circular cylindrical object coated with such meta- materials whose properties are determined according to two different, but identical, methods. The desired function is confirmed for both far-field and near-field cases with full wave simulations based on the finite element method. This work reveals a promising way to achieve noise shielding and naval camouflage.

关键词： superscattering acoustic waves finite element simulations

MODELING OF POWER TRANSMISSION THROUGH AN ELASTIC WALL BY PIEZOELECTRIC TRANSDUCERS AND acoustic waves

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MODELING OF POWER TRANSMISSION THROUGH AN ELASTIC WALL BY PI...

Analytical Solution for waves Propagation in Heterogeneous acoustic/Porous Media. Part I: The 2D Case

第三届全国压电和声波理论及器件技术研讨会

作者： Zeng-tao YANG,Shao-hua GUO Institute of Mechanics and Sensing Technology,School of Civil Engineering and Architecture Central South University,Changsha,Hunan 410083,China Yuan-tai HU Department of Mechanics,Huazhong University of Science and Technology,Wuhan,Hubei 430074,China Jia-shi YANG Department of Engineering Mechanics,University of Nebraska,Lincoln,NE 68588-0526,USA

We present our recent modeling results on power transmission through an elastic wall by piezoelectric transducers and acoustic waves,This includes the case of finite piezoelectric transducers on plates,power transmiss... 详细信息

关键词： Piezoelectricity transducer acoustic waves

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Communications in Computational Physics 2010年第3期7卷 171-194页

作者： Julien Diaz Abdelaaziz Ezziani Project-team Magique-3D INRIA Bordeaux Sud-Ouest LMA Pau CNRS UMR 5142I.P.R.A-Universit´e de Pau et des Pays de l’Adouravenue de l’Universit´e BP 1155-64013 PAU CEDEXFrance

Thanks to the Cagniard-de Hoop’s method we derive the solution to theproblem of wave propagation in an infinite bilayered acoustic/poroelastic media, wherethe poroelastic layer is modelled by the biphasic Biot’s model. This first part is dedi-cated to solution to the two-dimensional problem. We illustrate the properties of thesolution, which will be used to validate a numerical code.

关键词： Biot’s model poroelastic waves acoustic waves acoustic/poroelastic coupling ana-lytical solution Cagniard-de Hoop’s technique 2D

A three-dimensional hydroelasticity theory for ship structures in acoustic field of shallow sea

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Journal of Hydrodynamics 2013年第6期25卷 929-937页

作者：邹明松吴有生刘艳敏林长刚 China Ship Scientific Research Center

Nowadays the development of green ship technology requires the vibration and noise control of oceangoing ships. The three-dimensional hydroelasticity theory of ships was previously extended to include the effect of fluid compressibility. This enables the dynamic responses and the acoustic radiations of a ship excited by onboard machineries or fluid fluctuation loads to be predicted. In this paper the hydroelastic analysis and sonoelastic analysis methods are fixrther incorporated with the Green＇s function in the Pekeris ocean hydro-acoustic waveguide model to work out a three-dimensional sonoelastic analysis method for ships in the ocean hydro-acoustic environment. As examples, the sound radiations of a floating elastic spherical shell excited by a concentrated force and a traveling LNG ship excited by the propeller induced pulsating forces acting on the wetted bottom plate of the stem in the shallow sea environment are predicted. The influences of the free surface and the sea bed on the generalized hydrodynamic coefficients and the acoustic pressure distributions in fluid domain are illustrated and discussed.

关键词： hydroelasticity sonoelasticity acoustic waves shallow sea environment LNG ship

Multi-channel surface acoustic wave device and its application on all-fiber acousto-optic modulation

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Chinese Optics Letters 2010年第1期8卷 107-110页

作者：赵路明赵启大 Institute of Physics Nankai University Institute of Modern Optics Nankai University

The interaction of multi-channel surface acoustic waves （SAWs） and a guided optical wave in fiber is studied, and the corresponding coupled wave equations are derived. A novel two-channel SAW all-fiber acousto-optic... 详细信息

关键词： acoustic waves acoustics Acoustoelectric effects Wave equations

Current Fluctuations in a Semiconductor Quantum Dot with Large Energy Spacing

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Chinese Physics Letters 2014年第12期31卷 107-110页

作者： JEONG Heejun Department of Applied Physics Hanyang University Ansan 426-791 Korea

Current fluctuation in electronic systems has been extensively studied due to the fact that they can pro- vide further information of charge transport compared to the conventional conductance measurements. Shot noise is the non-equilibrium electrical fluctuation due to the discrete nature of carriers flowing through a device, reflecting correlation effects. A well-known shot noise power density as uncorrelated charge trans- mission is S - 2el, with I the average current. This Poissonian shot noise can be observed in sys- tems with a single tunnel barrier. Positive or neg- ative correlations between charged particles, induced by the Coulomb interaction and the Pauli exclusion principle, can enhance or suppress shot noise from the Poissonian value. Numerous experimental and the- oretical studies of the shot noise in mesoseopie sys- tems have been carried out on various devices such as self-assembled quantum dots, resonant tunnel- ing diodes,molecular junction devices, quan- tum point contacts,semiconductor quantum dots, and metal atomic chains. Externally driven exci- tations which affect shot noise properties were also investigated.

关键词： acoustic waves Noise pollution

The role of refocusing in dynamic X-wave formation during femtosecond laser filamentation in water

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Chinese Optics Letters 2010年第2期8卷 244-247页

作者：徐俊杰徐晗熊辉程亚徐至展刘伟伟陈瑞良 State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences Key Laboratory of Opto-Electronic Information Science and Technology Centre d'Optique Photonique er Laser(COPL)and Departement de Physiquede Genie Physique et d'OptiqueUniversite LavalQuebec

With the evolution of a laser pulse in water, the formation of a nonlinear X wave during femtosecond filamentation is investigated based on numerical simulations. In particular, we analyze the far-field angularly resolved spectra obtained for different temporal portions of the ultrashort pulse during its propagation. Our result shows that the refocusing of ultrashort pulse leads to the formation of dynamic X wave which essentially manifests itself as conical emission.

关键词： acoustic waves Computer simulation Light propagation Ultrashort pulses

Imaging for Borehole Wall by a Cylindrical Linear Phased Array

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Chinese Physics Letters 2010年第9期27卷 119-122页

作者：张碧星师芳芳吴先梅宫俊杰章成广 State Key Laboratory of acoustics Institute of Acoustics Chinese Academy of Sciences Beijing 100190 School of Geophysics and Oil Resources Yangtze University 3ingzhou 434023

A new ultrasonic cylindrical linear phased array （CLPA） transducer is designed and fabricated for the borehole wall imaging in petroleum logging based on the previous theoretical researches. First, the CLPA transducer, which is made up of numbers of the piezoelectric elements distributed on the surface of a cylinder uniformly, is designed and fabricated. By transmitting and receiving acoustic waves with 16 active elements and using different groups of the elements under the control of the electric system, the CLPA can scan all areas of the borehole wall dynamically and rapidly without a traditional mechanism around the borehole axis. Then, the theoretical and experimental investigations are conducted in detail for the borehole wall scanning and imaging by the steel pipe and casing borehole with defects distributed in different shapes and directions. It is shown by experiments that the CLPA transducer has good focusing characteristic and good resolution for the borehole wall imaging in acoustic logging.

关键词： acoustics acoustic waves

Effect of Time Delay on Binary Signal Detection via a Bistable System

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Chinese Physics Letters 2014年第2期31卷 9-12页

作者：曾令藻刘炳阳徐亦达李建龙 College of Environmental and Resource Sciences Zhejiang University Hangzhou 310029 Department of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027

The effect of time delay on binary signal detection via a bistable system in the presence of white or colored Gaussian noise is investigated. By defining the bit error rate based on the solution of the approximated Fokker- Planck equation, the detector performance is investigated theoretically and is verified by Monte Carlo simulation. It is shown that, when the system parameter or noise intensity is optimally chosen, the increasing time delay generally improves the system performance. It is also shown that it is more difficult to accurately predict the system performance with a larger time delay and correlation time. This may inspire more thorough investigations in cooperative effects of a nonlinear system and time delay on signal processing.

关键词： Numerical simulations acoustic waves Correlations Monte Carlo method Noise pollution Monte Carlo simulation Noise levels Cooperatives