Frequency-domain simulation of sound propagation in acoustically treated ducts with flow

Şirzai, Ahmet


Frequency-domain prediction of turbofan noise radiation
Özyörük, Yusuf; Alpman, E; Ahuja, V; Long, LN (2004-03-05)
This paper describes a frequency-domain numerical method for predicting noise radiation from ducted fans, including acoustic treatment and non-uniform background flow effects. The method solves the Euler equations linearized about a mean flow in the frequency domain. A pseudo-time derivative term is added to the frequency-domain equations so that a time marching technique can be employed to drive the acoustic field to steady state explicitly. This approach makes distributed parallel computing more viable fo...
Frequency effect on electrical and dielectric characteristics of In/Cu2ZnSnTe4/Si/Ag diode structure
Gullu, H. H.; Surucu, O. Bayrakli; Terlemezoğlu, Makbule; Yildiz, D. E.; Parlak, Mehmet (Springer Science and Business Media LLC, 2019-05-01)
In/Cu2ZnSnTe4/Si/Ag diode structure was fabricated by sputtering Cu2ZnSnTe4 (CZTTe) thin film layer on the Si layer with In front contact. The frequency dependent room temperature capacitance and conductance measurements were carried out to obtain detailed information of its electrical characteristics. Admittance spectra of the diode exhibited strong frequency dependence and the obtained values showed decreasing behavior with the increase in the applied frequency. The effect of interfacial film layer with s...
Frequency domain optimization of dry friction dampers used for earthquake vibration damping of buildings
Erişen, Zühtü Eren; Ciğeroğlu, Ender; Department of Mechanical Engineering (2012)
There are many active and passive vibration control techniques to reduce the effect of energy on structures which emerges during an earthquake and reduce the displacement of buildings that is caused by ground acceleration. Main advantage of passive vibration control techniques over active vibration control techniques is; no external power or a sensor is required for passive vibration control devices (PVCDs) and it results in lower installation and maintenance costs. However, PVCDs require a predefined optim...
Frequency-resolved spectroscopy of XB1323-619 using XMM-Newton data: detection of a reflection region in the disc
Balman, Şölen (Oxford University Press (OUP), 2010-09-21)
We present the frequency-resolved energy spectra (FRS) of the low-mass X-ray binary dipper XB1323-619 during persistent emission in four different frequency bands using an archival XMM-Newton observation. FRS method helps to probe the inner zones of an accretion disc. XB1323-619 is an Atoll source and a type-I burster. We find that the FRS is well described by a single blackbody component with kT in a range 1.0-1.4 keV responsible for the source variability in the frequency ranges of 0.002-0.04 and 0.07-0.3...
Frequency estimation of a single real-valued sinusoid: An invariant function approach
Candan, Çağatay; Çelebi, Utku (2021-08-01)
An invariant function approach for the computationally efficient (non-iterative and gridless) maximum likelihood (ML) estimation of unknown parameters is applied on the real-valued sinusoid frequency estimation problem. The main attraction point of the approach is its potential to yield a ML-like performance at a significantly reduced computational load with respect to conventional ML estimator that requires repeated evaluation of an objective function or numerical search routines. The numerical results ind...
Citation Formats
A. Şirzai, “Frequency-domain simulation of sound propagation in acoustically treated ducts with flow,” Middle East Technical University, 2000.