Cepstral deconvolution method for measurement of absorption and scattering coefficients of materials

Aslan, Gökhan
Several methods are developed to measure absorption and scattering coefficients of materials. In this study, a new method based on cepstral deconvolution technique is proposed. A reverberation room method standardized recently by ISO (ISO 17497-1) is taken as the reference for measurements. Several measurements were conducted in a physically scaled reverberation room and results are evaluated according to these two methods, namely, the method given in the standard and cepstral deconvolution method. Two methods differ from each other in the estimation of specular parts of room impulse responses essential for determination of scattering coefficients. In the standard method, specular part is found by synchronous averaging of impulse responses. However, cepstral deconvolution method utilizes cepstral analysis to obtain the specular part instead of averaging. Results obtained by both of these two approaches are compared for five different test materials. Both of the methods gave almost same values for absorption coefficients. On the other hand, lower scattering coefficient values have been obtained for cepstral deconvolution with respect to the ISO method.


Computer simulation of grain boundary grooving and cathode voiding n bamboo interconnects by surface diffusion under capillary and electromigration forces
Akyıldız, Öncü; Oğurtanı, Tarık Ö.; Department of Metallurgical and Materials Engineering (2004)
The processes of grain boundary grooving and cathode voiding which are important in determining the life times of thin films connecting the transistors in an integrated circuit are investigated by introducing a new mathematical model, which flows from the fundamental postulates of irreversible thermodynamics, accounting for the effects of applied electric field and thermal stresses. The extensive computer studies on the triple junction displacement dynamics shows that it obeys the first order reaction kinet...
Growth and characterization of thin sio2 and ta2o5 dielectric layers nd : yag laser oxidation
Aygün Özyüzer, Gülnur; Turan, Raşit; Department of Physics (2005)
Our aim was to establish a methodology for laser assisted oxidation of semiconductor and metal surfaces. One advantage of laser oxidation is the fact that radiation is heavily absorbed in a thin surface layer of the sample and the other is its ability for local oxidation. In addition to this, laser beam can be directed into some areas that other processes cannot reach. For these reasons, Nd:YAG pulsed laser working at 1064 nm wavelength is used for the oxidation purposes of Si and Ta films. First, SiO2 laye...
An experimental study on off-design performance and noise in small pumps
Şahin, Fatma Ceyhun; Eralp, O. Cahit; Department of Mechanical Engineering (2007)
This thesis study is focused on experimentally investigating pump noise at design and off-design operations and its relations with pressure fluctuations. Small size pumps are placed in a semi-anechoic chamber and operated at various system conditions and various rotational pump speeds. Pump operational data, noise data and time dependent pressure data are recorded. Fast Fourier Transform spectra of noise and pressure data are compared. Coherence spectrum between sound pressure level and hydraulic pressures ...
Analytical precision limits in slitless spectroscopy
Öktem, Sevinç Figen (2012-08-05)
We consider the problem of estimating emission line parameters from the measurements of a multi-order slitless spectrometer. This problem can be viewed as a multi-frame deblurring problem with shift variant Gaussian blur. By using Cramer-Rao lower bound theory, we derive analytical precision limits to this parameter estimation when the measurements are corrupted with Gaussian noise. The derivation involves an approximation to the Fisher information matrix in order to obtain closed-form expressions. An impor...
FEM solution of natural convection flow in square enclosures under magnetic field
Turk, O.; Tezer, Münevver (Emerald, 2013-01-01)
Purpose - The purpose of the paper is to obtain finite element method (FEM) solution of steady, laminar, natural convection flow in inclined enclosures in the presence of an oblique magnetic field. The momentum equations include the magnetic effect, and the induced magnetic field due to the motion of the electrically conducting fluid is neglected. Quadratic triangular elements are used to ensure accurate approximation for second order derivatives of stream function appearing in the vorticity equation.
Citation Formats
G. Aslan, “Cepstral deconvolution method for measurement of absorption and scattering coefficients of materials,” M.S. - Master of Science, Middle East Technical University, 2006.