Browsing by Subject "Waveform analysis"

Now showing 1 - 3 of 3

Open Access
Circuit theoretical method for efficient finite element analysis of acoustical problems
(IEEE, 1998) Ekinci, A. Suat; Atalar, Abdullah
In the last decade, there has been an outstanding improvement in the computer aided design tools for VLSI circuits regarding solution times and the circuit complexity. This study proposes formulating the acoustic field analysis problem using FEM, and employing the recent speed-up techniques used in the circuit simulators. In this work, total mass, stiffness and damping matrices are obtained using the FE approach, and piped into a computer program which generates an equivalent SPICE compatible circuit netlist. This approach makes it possible to use the most recent circuit simulation techniques to simulate the acoustical problems. The equivalent electrical circuit is a resistor-inductor-capacitor (RLC) circuit containing controlled sources to handle the couplings. The circuit matrices are 6 times larger but are sparser. We analyze these circuits with a general-purpose circuit simulation program, HSPICE, which provides high accuracy solutions in a short time. We also use an in-house developed circuit simulation program, MAWE, which makes use of asymptotic waveform evaluation (AWE) technique that has been successfully used in circuit simulation for solutions of large sets of equations. The results obtained on several problems, which are solved in time and frequency domains using circuit simulators and the FE analysis program ANSYS, match each other pretty well. Using circuit simulators instead of conventional method improves simulation speed without a significant loss of accuracy.
Open Access
Concept of T-wave morphology dispersion
(IEEE, 1999) Acar, Burak; Yi, G.; Malik, M.
The detection of ventricular repolarization abnormalities is widely being done using the QT interval measurements. However, there are both technical and theoretical problems with QT measurements. We propose two robust methods for the quantification of the ventricular repolarization abnormalities: i) The quantification of the inter-lead morphology differences of the T wave (T Wave Morphology Dispersion - TMD) ii) The analysis of the T wave wavefront direction with respect to the QRS complex (Total Cosine R_To_T - TCRT). Sensitivity and specificity of 82% (84%) in supine position and 77% (79%) in standing position were achieved for TMD (TCRT). Both parameters were more reproducible than conventional QT interval based parameters.
Open Access
Effect of cross-sectional geometry on the RPA plasmons of quantum wires
(Pergamon Press, 1994) Bennett, C. R.; Tanatar, Bilal; Constantinou, N. C.; Babiker, M.
The effect of cross-sectional geometry on both the intrasubband plasmon and intersubband plasmon of a quantum wire is investigated within a two-subband RPA scheme. Exact analytical electronic wavefunctions for circular, elliptical and rectangular wires are employed within the infinite barrier approximation. It is found that for fixed cross-sectional area and linear electron concentration, the intrasubband plasmon energy is only marginally dependent on the wire geometry whereas the intersubband plasmon energy may change considerably due to its dependence on the electronic subband energy difference. © 1994.