Prof. Alireza Baghai-Wadji Profile

Prof. Alireza Baghai-Wadji

at Royal Melbourne Institute of Technology

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Publications (5)

Proceedings Article | 30 December 2008 Paper

A scheme to calculate higher-order homogenization as applied to micro-acoustic boundary value problems

Hardik Vagh, Alireza Baghai-Wadji

Proceedings Volume 7269, 72690Q (2008) https://doi.org/10.1117/12.814424

KEYWORDS: Homogenization, Finite element methods, Composites, Partial differential equations, Materials science, Standards development, Computer engineering, Manufacturing, Nanotechnology, Materials processing

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Proceedings Article | 30 December 2008 Paper

Construction of Wannier functions in phononic structures

M. Muradoglu, Alireza Baghai-Wadji

Proceedings Volume 7269, 72690R (2008) https://doi.org/10.1117/12.814452

KEYWORDS: Acoustics, Wave propagation, Fourier transforms, Transform theory, Solids, Modeling and simulation, Linear algebra, Signal processing, Velocity measurements, Analytical research

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Proceedings Article | 30 December 2008 Paper

A numerical technique for solving Schrödinger's Equation in molecular electronic applications

A. Smith, A. Baghai-Wadji

Proceedings Volume 7268, 72681Q (2008) https://doi.org/10.1117/12.814318

KEYWORDS: Oscillators, Molecular electronics, Solids, Differential equations, Modeling, Testing and analysis, Numerical analysis, Computer engineering, Smart structures, Current controlled current source

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Proceedings Article | 30 December 2008 Paper

A novel approach for symbolically calculating polynomial integrals arising in 2D and 3D FEM applications

Alireza Baghai-Wadji, Istiaque Ahmed

Proceedings Volume 7269, 72690S (2008) https://doi.org/10.1117/12.814698

KEYWORDS: Finite element methods, 3D applications, Microelectronics, Device simulation, Telecommunications, Electronic components, Medium wave, Acoustics, Signal processing, Computer simulations

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Proceedings Article | 30 December 2008 Paper

Joint time-frequency analysis of micro-acoustic devices

Glenn Matthews, Alireza Baghai-Wadji

Proceedings Volume 7269, 72690Y (2008) https://doi.org/10.1117/12.814462

KEYWORDS: Finite element methods, Acoustics, Time-frequency analysis, Wave plates, Fourier transforms, Modulation, Amplitude modulation, Wave propagation, Signal analyzers, Electrodes

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In this paper, a novel analysis technique for the performance evaluation of micro-acoustic devices has been proposed. Whereas traditional techniques typically focus solely on the frequency domain characteristics, we employ a Joint Time-Frequency Analysis (JTFA), which has been shown to provide a more complete characterisation of overall device performance and underlying physical phenomena. Although an emphasis is placed on a Flexural Plate Wave (FPW) device, the analysis technique presented is applicable to a wider range of micro-acoustic devices including Surface Acoustic Wave (SAW) structures and Thin-Film Bulk Acoustic Wave Resonators (TFBARs). SAWdevices, and indeed general filters, are typically described by a frequency domain characteristic, whereby the entire time domain information is discarded. This type of analysis assumes that the device has reached quasistationary conditions. By employing JTFA, the device performance can simultaneously be studied as a function of both time and frequency. This type of analysis is typically useful where spurious acoustic modes are generated which may influence the overall filter characteristic. We have investigated the functional properties of various JTFA kernels, including those appearing in the Wigner-Ville, Choi-Williams and Page distributions. A known deficiency associated with JTFA is the appearance of a number of spurious cross-terms in the computations. Whereas the cross-terms are relatively simple to detect for "monochromatic" (single-component) signals, it is not a trivial task to minimise such artifacts for "polychromatic" (multi-component) signals, which are typical in micro-acoustic devices. We propose novel methods for reducing the cross-terms interference appearing in JTFA, thereby improving the performance of the analysis technique. To investigate the application of the proposed technique, the simulated time domain response of a FPW device was investigated. The Finite Element Method (FEM) package ANSYS 8.0 was utilised to obtain the impulse response of the FPW structure under a dynamic transient analysis. A comparison is also made with the spectral domain Green's function to verify the FEM solution, where excellent agreement is obtained. Based on the FEM solutions, the insertion loss characteristics is calculated which represents a commonly applied frequency domain method of analysing micro-acoustic devices. A comparison has been made between the insertion loss characteristics and the proposed approach, where it is clearly demonstrated that the problem-adapted technique provides significantly more detailed information.

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