Browsing Dept. of Electrical and Electronics Engineering - Ph.D. / Sc.D. by Title
Now showing items 61-80 of 135
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Laser wavelength upconversion with optical parametric oscillators using simultaneously phase-matched crystals
(Bilkent University, 2002)In this thesis, we present our work on optical parametric oscillators that employ a single nonlinear crystal that is simultaneously-phase-matched for second-harmonic or sum-frequency generation in order to obtain frequency ... -
Linear quadratic control for harmonic signals
(Bilkent University, 2001) -
Local signal decomposition based methods for the calculation of three-dimensional scalar optical diffraction field due to a field given on a curved surface
(Bilkent University, 2013)A three-dimensional scene or object can be optically replicated via the threedimensional imaging and display method holography. In computer-generated holography, the scalar diffraction field due to a field given on an ... -
Low-frequency conductivity imaging using MRI gradient induced currents
(Bilkent University, 2016-09)Due to the switching of Magnetic Resonance Imaging (MRI) gradient fields, electric fields are induced in imaged subjects which give rise to `subject eddy currents'. The feasibility of low-frequency conductivity imaging ... -
Lumped element modeling of circular CMUT in collopsed mode
(Bilkent University, 2014)Capacitive micromachined ultrasonic transducer is a microelectromechanical device, which serves as an acoustic signal source or sensor, in a variety of applications including medical ultrasound imaging, ultrasound therapy, ... -
Magnetic resonance technologies based on reverse polarization for image-guided interventions
(Bilkent University, 2010)In this PhD dissertation, we presented four magnetic resonance (MR) technologies established upon reverse polarization for image guided interventions. The first three studies are based on tracking interventional devices, ... -
Maximum likelihood estimation of robust constrained Gaussian mixture models
(Bilkent University, 2013)Density estimation using Gaussian mixture models presents a fundamental trade off between the flexibility of the model and its sensitivity to the unwanted/unmodeled data points in the data set. The expectation ... -
Metasurface microlens focal plane arrays and mirrors
(Bilkent University, 2017-02)Lenses, mirrors and focal plane arrays (FPAs) are among the key components a ecting the functionality, performance and cost of electro-optical (EO) systems. Conventional lenses rely on phase accumulation mechanism for ... -
Method of moments analysis of microstrip antennas in cylindrically stratified media using closed-form Green's functions
(Bilkent University, 2012)Numerical methods based on Method of Moments (MoM) have been widely used for the design and analysis of planar microstrip antennas/arrays and printed circuits for various applications for many years. On the other hand, ... -
Modeling and characterization of capacitive micromachined ultrasonic transducers
(Bilkent University, 2000)The Capacitive Micromachined Ultrasonic Transducer (cMUT) is a device used for the generation and detection of ultrasonic sound waves. The device is constructed on a silicon substrate using a microfabrication process. ... -
Motion artifact reduction techniques in magnetic resonance imaging
(Bilkent University, 1991)It is shown that the expansion/shrinkage and rotational motions of the body cause phase and amplitude distortions and non-rectangular sampling over the A:-domain. If these distortions are not compensated then the reconstructed ... -
Multi-layer traffic engineering in optical networks under physical layer impairments
(Bilkent University, 2010)We study Traffic Engineering (TE) in Multiprotocol Label Switching (MPLS)/Wavelength Division Multiplexing (WDM) networks and propose a multi-layer TE method. MPLS provides powerful TE features for IP networks and is ... -
Multichannel and phase based magnetic resonance electrical properties tomography
(Bilkent University, 2016-09)Imaging of electrical properties (EPs, i.e. conductivity and dielectric permittivity) of tissues give valuable information about the physiological and pathological conditions of tissues. Among the EP imaging modalities, ... -
Nanomechanical characterization of materials by enhanced higher harmonics of a tapping cantilever
(Bilkent University, 2005)In a tapping-mode atomic force microscope, the periodic interaction of the tip with the sample surface creates a tip-sample interaction force, and the pure sinusoidal motion of the cantilever is disturbed. Hence, the ... -
Nanosecond upconversion optical parametric oscillators
(Bilkent University, 2005)In this thesis, we demonstrate a technique for highly efficient red beam generation using nanosecond upconversion optical parametric oscillators based on KTiOAsO4 crystals that are simultaneously phase matched for optical ... -
New methods for robust speech recognition
(Bilkent University, 1995)New methods of feature extraction, end-point detection and speech enhcincement are developed for a robust speech recognition system. The methods of feature extraction and end-point detection are based on wavelet analysis ... -
A new signal detection method for capacitive micromachined ultrasonic transducers
(Bilkent University, 1999)Capacitive micromachined ultrasonic transducers (cMUT) have become an alternative to piezoelectric transducers in the past few years. They are constructed by integrating many small circular membranes in parallel. In this ... -
New techniques for ventricular repolarization and heart rate variability analyses
(Bilkent University, 2000)This thesis is composed of two parts: i) Development of a fully automatic Heart Rate Variability (HRV) analysis method, and ii) development of new methods for ventricular repolarization (T wave) analysis. The first part ... -
New techniques to design performance improved power dividers and directional couplers using the new scattering parameter relations
(Bilkent University, 2015)Wide bandwidth provides with several benefits in RF applications such as enabling high data rates for communication applications, enhancing the multi tread avoiding capabilities of the jamming systems, improving the ... -
Noise analysis of interdigital cantilevers for atomic force microscopy
(Bilkent University, 1998)Atomic force microscoiDe (AFM) is proved to be a powerful tool for atomic resolution surface imaging. The most crucial parts of an AFM system are the cantilever with an integrated tip and the deflection detection sensor. ...
