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Nazmi Yilmaz

Publications and source records attributed to Nazmi Yilmaz.

2 recordsLinked to original sources

EEG Brain mapping based on the Duffing oscillator

This study proposes a Duffing oscillator based measurement framework for detecting frequency components associated with postsynaptic potential related activity in EEG recordings. The Duffing oscillator is employed as a nonlinear measurement system whose high sensitivity to weak periodic inputs enables robust frequency estimation in the presence of strong noise. Because postsynaptic potentials are embedded in noisy EEG recordings, they are treated as weak signals. Based on the detected weak-signal frequency distributions across EEG channels, topographic maps of brain activity are constructed to visualize spatial variations in neural activation. For this purpose, EEG signals recorded from two musicians and two audience members during a music experiment were analysed. The frequency components of the weak signals were searched within the 4 37 Hz range across all EEG channels. Subsequently, topographic brain maps were generated according to the number of detected weak-signal components. The results indicate that Duffing oscillator based weak signal detection is an effective tool for EEG brain mapping. Compared with Fourier and wavelet-based methods, the proposed technique provides a more detailed representation of brain activation. These findings suggest that the proposed approach has potential for investigating various pathological conditions and for enhancing the understanding of cognitive and behavioural functions of the human brain.

physics.soc-ph

Broadband polarization-independent low-crosstalk metasurface lens array-based mid wave infrared focal plane arrays

The miniaturization of pixel is essential for achieving high-resolution, planar, compact-size focal plane arrays (FPAs); however, the resulted increase in the optical crosstalk between adjacent pixels leads to serious drawback and trade-off. In the current work, we design and propose an efficient broadband polarization-insensitive all-dielectric metasurface lens array-based focal plane arrays (FPA) operating in the mid-wave infrared (MWIR). High focusing efficiency over 0.85 with superior optical crosstalk performance is achieved. We demonstrated that optical crosstalk can be reduced to low levels below 2.8% with high efficiency. For the device performance, a similar figure-of-merit (FoM) from the previous reports was used and our device achieved FoM of 91 which outperformed all other types MWIR FPAs designed so far. Proposed metasurface lens arrays demonstrate great potential for increasing the signal to noise ratio and sensitivity thus paving the way for compact-size, high-resolution FPAs.

physics.optics