The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Tribikram Kundu - One of the best experts on this subject based on the ideXlab platform.
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Ultrasonic Field modeling a comparison of analytical semi analytical and numerical techniques
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2010Co-Authors: Tribikram Kundu, Dominique Placko, Ehsan Kabiri Rahani, Tamaki YanagitaAbstract:Modeling Ultrasonic Fields in front of a transducer in the presence and absence of a scatterer is a fundamental problem that has been attempted by different techniques: analytical, semi-analytical, and numerical. However, a comprehensive comparison study among these techniques is currently missing in the literature. The objective of this paper is to make this comparison for different Ultrasonic Field modeling problems with various degrees of difficulty. Four fundamental problems are considered: a flat circular transducer, a flat square transducer, a circular concave transducer, and a point focused transducer (concave lens) in the presence of a cavity. The Ultrasonic Field in front of a finite-sized transducer can be obtained by Huygens-Fresnel superposition principle that integrates the contributions of several point sources distributed on the transducer face. This integral which is also known as the Rayleigh integral or Rayleigh-Sommerfeld integral (RSI) can be evaluated analytically for obtaining the pressure Field variation along the central axis of the transducer for simple geometries, such as a flat circular transducer. The semi-analytical solution is a newly developed mesh-free technique called the distributed point source method (DPSM). The numerical solution is obtained from finite element analysis. Note that the first three problems study the effect of the transducer size and shape, whereas the fourth problem computes the Field in presence of a scatterer.
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Ultrasonic Field modeling by distributed point source method for different transducer boundary conditions
Journal of the Acoustical Society of America, 2009Co-Authors: Tamaki Yanagita, Tribikram Kundu, Dominique PlackoAbstract:Several investigators have modeled Ultrasonic Fields in front of transducers by Huygens–Fresnel superposition principle that integrates the contributions of a number of point sources distributed on the transducer face. This integral solution, also known as the Rayleigh integral or Rayleigh–Sommerfeld Integral solution, assumes the strengths of the point sources distributed over the transducer face. A newly developed technique called distributed point source method (DPSM) offers an alternative approach for modeling Ultrasonic Fields. DPSM is capable of modeling the Field for prescribed source strength distribution as well as for prescribed interface conditions with unknown source strengths. It is investigated how the Ultrasonic Field in front of the transducer varies in different situations: (1) when the point source strengths are known, (2) when the point source strengths are unknown but obtained from the interface condition that only the normal component of the transducer velocity is continuous across th...
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Effect of transducer boundary conditions on the generated Ultrasonic Field
Health Monitoring of Structural and Biological Systems 2008, 2008Co-Authors: Tamaki Yanagita, Dominique Placko, Tribikram KunduAbstract:ABSTRACT Several investigators have modeled Ultrasonic Fields in front of finite sized transducers. Most of these models are based on Huygens principle. Following Huygens-Fresnel superposition principle one can assume that the total Field of a finite size transducer is obtained by simply superimposing the contributions of a number of point sources uniformly distributed on the transducer face. If the point source solution, also known as the Greens function, is known then integrating that point source solution over the transducer face one can obtain the total Ultrasonic Field generated by a finite transducer. This integral is known as Rayleigh-SommerField integral. It is investigated here how the Ultrasonic Field in front of the transducer varies for different interface conditions at the transducer face-fluid interface such as 1) when only the normal component of the transducer velocity is assumed to be uniform on the transducer face and continuous across the fluid-solid interface, or 2) when all three components of velocity are assumed to be uniform on the transducer face and continuous across the interface, 3) when the pressure instead of velocity is assumed to be uniform on the transducer face and continuous across the interface. All these different boundary and interface conditions can be modeled by the newly developed Distributed Point Source Method (DPSM). These results are compared with the Rayleigh-SommerField integral representation that gives the fluid pressure in front of the transducer when the transducer-fluid interface is subjected to uniform normal velocity. Keywords: Distributed Point Source Method, DPSM, Ultrasonic Field, Modeling
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Ultrasonic Field modeling in plates immersed in fluid
International Journal of Solids and Structures, 2007Co-Authors: Sourav Banerjee, Tribikram KunduAbstract:Abstract Distributed Point Source Method (DPSM) is a semi-analytical technique that can be used to calculate the Ultrasonic Field (pressure, velocity and displacement Fields in a fluid, or stress and displacement Fields in a solid) generated by Ultrasonic transducers. So far the technique has been used to model Ultrasonic Fields in homogeneous and multilayered fluid structures, and near a fluid–solid interface when a solid half-space is immersed in a fluid. In this paper, the method is extended to model the Ultrasonic Field generated in a homogeneous isotropic solid plate immersed in a fluid. The objective of this study is to model the generation of guided waves in a solid plate when Ultrasonic beams from transducers of finite dimension strike the plate at different critical angles. DPSM results for a solid half-space problem are compared with the finite element predictions to show the superiority of the DPSM technique. The predicted results are also compared with the experimental visualization of the mode patterns of Lamb waves propagating in a glass plate obtained from stroboscopic photoelastic method. Experimental and theoretical results show good qualitative agreement. The DPSM technique is then applied to study the mode patterns in aluminum plates immersed in water.
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dpsm technique for Ultrasonic Field modelling near fluid solid interface
Ultrasonics, 2007Co-Authors: Sourav Banerjee, Tribikram Kundu, Nasser AlnuaimiAbstract:Abstract Distributed point source method (DPSM) is gradually gaining popularity in the Field of non-destructive evaluation (NDE). DPSM is a semi-analytical technique that can be used to calculate the Ultrasonic Fields produced by transducers of finite dimension placed in homogeneous or non-homogeneous media. This technique has been already used to model Ultrasonic Fields in homogeneous and multi-layered fluid structures. In this paper the method is extended to model the Ultrasonic Fields generated in both fluid and solid media near a fluid–solid interface when the transducer is placed in the fluid half-space near the interface. Most results in this paper are generated by the newly developed DPSM technique that requires matrix inversion. This technique is identified as the matrix inversion based DPSM technique. Some of these results are compared with the results produced by the Rayleigh–SommerField integral based DPSM technique. Theory behind both matrix inversion based and Rayleigh–SommerField integral based DPSM techniques is presented in this paper. The matrix inversion based DPSM technique is found to be very efficient for computing the Ultrasonic Field in non-homogeneous materials. One objective of this study is to model Ultrasonic Fields in both solids and fluids generated by the leaky Rayleigh wave when finite size transducers are inclined at Rayleigh critical angles. This phenomenon has been correctly modelled by the technique. It should be mentioned here that techniques based on paraxial assumptions fail to model the critical reflection phenomenon. Other advantages of the DPSM technique compared to the currently available techniques for transducer radiation modelling are discussed in the paper under Introduction.
Jun Chen - One of the best experts on this subject based on the ideXlab platform.
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single walled carbon nanotube reinforced copper composite coatings prepared by electrodeposition under Ultrasonic Field
Materials Letters, 2008Co-Authors: C. S. He, J. N. Deng, Y. D. Wang, Y L Yang, Jun ChenAbstract:Single-walled carbon nanotube-reinforced Cu composite coatings prepared by electrochemical deposition under Ultrasonic Field exhibit smaller crystallite size and higher lattice micro-strain compared with a pure Cu coating. The as-deposited coatings retain a good electrical conductivity comparable to pure copper and simultaneously show a significant enhancement in mechanical properties. This indicates that the present electrochemical deposition technique can be used for preparing the carbon nanotube-reinforced metals with enhanced mechanical and functional properties.
Y L Yang - One of the best experts on this subject based on the ideXlab platform.
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single walled carbon nanotube reinforced copper composite coatings prepared by electrodeposition under Ultrasonic Field
Materials Letters, 2008Co-Authors: C. S. He, J. N. Deng, Y. D. Wang, Y L Yang, Jun ChenAbstract:Single-walled carbon nanotube-reinforced Cu composite coatings prepared by electrochemical deposition under Ultrasonic Field exhibit smaller crystallite size and higher lattice micro-strain compared with a pure Cu coating. The as-deposited coatings retain a good electrical conductivity comparable to pure copper and simultaneously show a significant enhancement in mechanical properties. This indicates that the present electrochemical deposition technique can be used for preparing the carbon nanotube-reinforced metals with enhanced mechanical and functional properties.
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Single-walled carbon nanotube-reinforced copper composite coatings prepared by electrodeposition under Ultrasonic Field
Materials Letters, 2008Co-Authors: Y L Yang, C. S. He, J. N. Deng, J. Nan, Y. Ren, J. G. Chen, Y. D. Wang, Liang ZuoAbstract:Single-walled carbon nanotube-reinforced Cu composite coatings prepared by electrochemical deposition under Ultrasonic Field exhibit smaller crystallite size and higher lattice micro-strain compared with a pure Cu coating. The as-deposited coatings retain a good electrical conductivity comparable to pure copper and simultaneously show a significant enhancement in mechanical properties. This indicates that the present electrochemical deposition technique can be used for preparing the carbon nanotube-reinforced metals with enhanced mechanical and functional properties. © 2007 Elsevier B.V. All rights reserved.
Chuhyung Chen - One of the best experts on this subject based on the ideXlab platform.
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influences of a bipolar membrane and an Ultrasonic Field on alkaline water electrolysis
Journal of Membrane Science, 2012Co-Authors: Chi Yuan Hung, Chengchien Wang, Chuhyung ChenAbstract:Abstract The energy efficiency of alkaline water electrolysis improved by using the polyvinylidene fluoride-grafted 2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxyl-propyl ester bipolar membrane (PVDF-g-G-I BM) as diaphragms with an Ultrasonic Field (USF) has been explored in this study. The PVDF-g-G-I BM was prepared by the plasma-induced polymerization method. The method utilized the porous PVDF membrane as substrates, and G-I monomer was grafted onto both sides of the PVDF membrane after plasma treatment. The performance of the PVDF-g-G-I BM was demonstrated by measuring the cell voltage for the cell operated with or without an USF. According to steady-state E – I curves, the order of the cell voltage for alkaline water electrolysis was the DuPont commercial membrane > Water > PVDF-g-G-I BM under the same working condition. The PVDF-g-G-I BM was found to function well as a diaphragm in alkaline water electrolysis. In comparison with Water without an USF, the H 2 production efficiency by using the PVDF-g-G-I BM was improved 5–16/4% and an energy saving of ca. 15–20% (13–18%)/8–12% (6–10%) can be reached in alkaline water electrolysis at 0.5 M (1.0 M) NaOH for the cell operated with/without an USF, respectively.
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water electrolysis in the presence of an Ultrasonic Field
Electrochimica Acta, 2009Co-Authors: Chengchien Wang, Chuhyung ChenAbstract:Abstract The energy efficiency of water electrolysis has been considerably improved in the presence of an Ultrasonic Field. This was demonstrated by measuring the cell voltage, efficiency and energy consumption of the generated gas from the electrolysis. These measurements were carried out in alkaline solution using linear sweep voltammetry (LSV) and galvanostatic polarization techniques. A large reduction of the cell voltage was achieved under the Ultrasonic Field, especially at high current density and low electrolyte concentration. With the same current density, the cell voltage difference with and without the Ultrasonic Field fell as the concentration of the electrolyte was increased. The efficiency of H 2 generation was improved at a range of 5–18% at high current density in the Ultrasonic Field but the efficiency of O 2 generation fell a little due to the difference in the behavior of the gas bubbles. The energy saving for H 2 production by using the Ultrasonic Field was about 10–25% for a certain concentration of the electrolyte when a high current density was used. On the other hand, the energy consumption for O 2 production with and without the Ultrasonic Field was almost the same.
C. S. He - One of the best experts on this subject based on the ideXlab platform.
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single walled carbon nanotube reinforced copper composite coatings prepared by electrodeposition under Ultrasonic Field
Materials Letters, 2008Co-Authors: C. S. He, J. N. Deng, Y. D. Wang, Y L Yang, Jun ChenAbstract:Single-walled carbon nanotube-reinforced Cu composite coatings prepared by electrochemical deposition under Ultrasonic Field exhibit smaller crystallite size and higher lattice micro-strain compared with a pure Cu coating. The as-deposited coatings retain a good electrical conductivity comparable to pure copper and simultaneously show a significant enhancement in mechanical properties. This indicates that the present electrochemical deposition technique can be used for preparing the carbon nanotube-reinforced metals with enhanced mechanical and functional properties.
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Single-walled carbon nanotube-reinforced copper composite coatings prepared by electrodeposition under Ultrasonic Field
Materials Letters, 2008Co-Authors: Y L Yang, C. S. He, J. N. Deng, J. Nan, Y. Ren, J. G. Chen, Y. D. Wang, Liang ZuoAbstract:Single-walled carbon nanotube-reinforced Cu composite coatings prepared by electrochemical deposition under Ultrasonic Field exhibit smaller crystallite size and higher lattice micro-strain compared with a pure Cu coating. The as-deposited coatings retain a good electrical conductivity comparable to pure copper and simultaneously show a significant enhancement in mechanical properties. This indicates that the present electrochemical deposition technique can be used for preparing the carbon nanotube-reinforced metals with enhanced mechanical and functional properties. © 2007 Elsevier B.V. All rights reserved.
