Transmission Loss Investigation of Two-Dimensional Thin Mufflers by the Modal Expansion Method Using a New Line Source Model

2011 ◽  
Vol 97 (1) ◽  
pp. 54-61 ◽  
Author(s):  
Lin Li ◽  
Cheng Guang-Xu ◽  
Siu-Kit Lau ◽  
Li Yun ◽  
Gu Zhao-Lin
Keyword(s):  
Line Source ◽  
Transmission Loss ◽  
Expansion Method ◽  
Source Model ◽  
Two Dimensional ◽  
Modal Expansion ◽  
Modal Expansion Method ◽  
Line Source Model

Two‐dimensional induction log modeling using a coupled‐mode, multiple‐reflection series method

Geophysics ◽  
1993 ◽  
Vol 58 (4) ◽  
pp. 466-474 ◽  
Author(s):  
David M. Pai ◽  
J. Ahmad ◽  
W. David Kennedy
Keyword(s):  
Separation Of Variables ◽  
Expansion Method ◽  
Multiple Reflection ◽  
Two Dimensional ◽  
Multiple Reflections ◽  
Vertical Coordinate ◽  
Modal Expansion ◽  
Coupled Mode ◽  
Modal Expansion Method ◽  
Method Of Solution

In induction logging, both vertical and radial conductivity variations exist in the logged medium; elementary separation of variables cannot be applied directly to the partial differential equation describing the electromagnetic field in such a medium. A modal expansion method of solution can be designed using modes defined with respect to the vertical coordinate. This method breaks the original two‐dimensional (2-D) problem into a set of independent one‐dimensional (1-D) problems. The receiver signal is decomposed into a direct signal traveling within the borehole and a reflection signal bearing information about the conductivity distribution outside the borehole. The solution is obtained as a coupled‐mode, multiple‐reflection series accounting for repeated mode reflections at the vertical boundaries in the medium. Each term in the series represents the next higher order reflection in a sequence of multiple reflections; results show two terms are sufficient to reach accuracy acceptable for log modeling.

Analytic solutions of the scattering by two multilayered dielectric spheres

1992 ◽  
Vol 70 (9) ◽  
pp. 696-705 ◽  
Author(s):  
A-K. Hamid ◽  
I. R. Ciric ◽  
M. Hamid
Keyword(s):  
Boundary Conditions ◽  
Cross Sections ◽  
Plane Electromagnetic Wave ◽  
Expansion Method ◽  
Analytic Solutions ◽  
Addition Theorem ◽  
Modal Expansion ◽  
Modal Expansion Method ◽  
Dielectric Spheres ◽  
Scattered Fields

The problem of plane electromagnetic wave scattering by two concentrically layered dielectric spheres is investigated analytically using the modal expansion method. Two different solutions to this problem are obtained. In the first solution the boundary conditions are satisfied simultaneously at all spherical interfaces, while in the second solution an iterative approach is used and the boundary conditions are satisfied successively for each iteration. To impose the boundary conditions at the outer surface of the spheres, the translation addition theorem of the spherical vector wave functions is employed to express the scattered fields by one sphere in the coordiante system of the other sphere. Numerical results for the bistatic and back-scattering cross sections are presented graphically for various sphere sizes, layer thicknesses and permittivities, and angles of incidence.

Prediction of Sound Transmission Loss for Finite Sandwich Panels Based on a Test Procedure on Beam Elements

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Zhongchang Qian ◽  
Daoqing Chang ◽  
Bilong Liu ◽  
Ke Liu
Keyword(s):  
Sandwich Panel ◽  
Transmission Loss ◽  
Test Procedure ◽  
Sandwich Panels ◽  
Sound Transmission ◽  
Expansion Method ◽  
Bending Stiffness ◽  
Sound Transmission Loss ◽  
Modal Expansion ◽  
Beam Elements

An approach on the prediction of sound transmission loss for a finite sandwich panel with honeycomb core is described in the paper. The sandwich panel is treated as orthotropic and the apparent bending stiffness in two principal directions is estimated by means of simple tests on beam elements cut from the sandwich panel. Utilizing orthotropic panel theory, together with the obtained bending stiffness in two directions, the sound transmission loss of simply-supported sandwich panel is predicted by the modal expansion method. Simulation results indicated that dimension, orthotropy, and loss factor may play important roles on sound transmission loss of sandwich panel. The predicted transmission loss is compared with measured data and the agreement is reasonable. This approach may provide an efficient tool to predict the sound transmission loss of finite sandwich panels.

Vibration Control of a Multi-Layer Piezoelectric Cylindrical Shell

1997 ◽  
Author(s):  
Jinhao Qiu ◽  
Junji Tani
Keyword(s):  
Cylindrical Shell ◽  
Feedforward Control ◽  
Equations Of Motion ◽  
Good Control ◽  
Expansion Method ◽  
Piezoelectric Sensor ◽  
State Equation ◽  
Integrated Sensor ◽  
Modal Expansion ◽  
Modal Expansion Method

Abstract Equations of motion for multi-layer piezoelectric cylindrical shells and the equations of the integrated piezoelectric sensors are derived. The state equation is obtained by solving the equations of motion with modal expansion method. The feedback control, feedforward control, and their combination are applied in the control of forced vibration of the piezoelectric cylindrical shell with integrated sensor and actuators. The simulation and experimental results show that good control effectiveness can be obtained by using the integrated piezoelectric sensor and actuators in conjunction with the combination of feedback and feedforward control methods.

Modal expansion method of analysis for slot-coupled microstrip antenna

1989 ◽  
Vol 25 (20) ◽  
pp. 1338 ◽  
Author(s):  
A. Ittipiboon ◽  
R. Oostlander ◽  
Y.M.M. Antar
Keyword(s):  
Microstrip Antenna ◽  
Expansion Method ◽  
Modal Expansion ◽  
Modal Expansion Method

Evaluating actuator distributions in simply supported truncated thin conical shell with embedded piezoelectric layers

2018 ◽  
Vol 29 (12) ◽  
pp. 2641-2659 ◽  
Author(s):  
Rasa Jamshidi ◽  
Ali A Jafari
Keyword(s):  
Conical Shell ◽  
Piezoelectric Layer ◽  
Cone Angle ◽  
Expansion Method ◽  
Longitudinal Direction ◽  
Modal Expansion ◽  
Simply Supported ◽  
Modal Expansion Method ◽  
Layer Segmentation ◽  
Distributed Actuator

In this investigation, distributed modal actuator forces of simply supported truncated conical shell embedded by a piezoelectric layer are studied. Piezoelectric layer is distributed on the conical shell surface as actuators. Three types of distributions are considered: longitudinal, circumferential, and diagonal distributions. First, electromechanical equations of the conical shell with embedded piezoelectric actuator layer are extracted. Then modal expansion method is used to define independent modal characteristics of the conical shell. For each kind of distribution, three case studies are considered and evaluated. Results showed that in the longitudinal and diagonal distributed actuator, membrane force in the longitudinal direction is the dominant force and in the circumferential distributed actuator, the membrane force in the circumferential direction is the dominant force. The effects of cone angle, piezoelectric thickness, and piezoelectric layer segmentation on modal forces of each distributed actuator are also studied. In circumferential distributed actuator, modal forces increase as the cone angle increases. This phenomenon in the longitudinal and diagonal distributed actuator is almost reversed. The piezoelectric layer segmentation effect on the modal forces distribution is also evaluated, and it showed that this phenomenon has a critical effect on the modal forces distribution.

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