Electrical & Electronics Engineering

Permanent URI for this collectionhttps://hdl.handle.net/10679/9148

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    Blood clotting time measurement using a miniaturized high-frequency ultrasound sensor
    (IEEE, 2023) Sobhani, M. R.; Majidi, Negar; Yaralıoğlu, Göksen Göksenin; Electrical & Electronics Engineering; YARALIOĞLU, Göksen Göksenin; Majidi, Negar
    This paper demonstrates a novel blood coagulation time measurement methodology that requires as low as 1 microliter of whole blood. The blood sample is placed on the top surface of a fused quartz plate where an ultrasonic transducer is fabricated on the bottom surface. The location of the blood sample is aligned with the transducer; therefore, the reflected acoustic waves from the blood/quartz interface are captured and converted to electrical signals by the transducer. The transducer is made of an 8 μm thick zinc oxide (ZnO) thin film that operates at 400 MHz. The acoustic impedance of blood changes due to the coagulation process. This affects the reflection coefficient and amplitude of the reflected waves from the blood/quartz interface. Thus, the blood coagulation time is determined by monitoring the amplitude of reflected acoustic waves. In the experiments, whole blood was used without any sample preparation. The method was tested using citrated blood with calcium chloride and activated partial thromboplastin (aPTT) reagents. We observed that aPTT coagulation times lengthened from 25 sec. to 47 sec. with the addition of heparin. The proposed method has the potential to be used in a disposable low-cost portable coagulation time measurement cartridge for patient self-testing.
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    Development and 3D spatial calibration of a parallel robot for percutaneous needle procedures with 2D ultrasound guidance
    (World Scientific, 2017-12-01) Ahmad, Mirza Awais; Orhan, Sabri Orçun; Yıldırım, Mehmet Can; Bebek, Özkan; Mechanical Engineering; BEBEK, Özkan; Ahmad, Mirza Awais; Orhan, Sabri Orçun; Yıldırım, Mehmet Can
    Robotic systems are being applied to medical interventions as they increase the operational accuracy. The proposed autonomous and ultrasound guided 5-DOF parallel robot can achieve such accuracy for needle biopsies, which particularly demand precise needle positioning and insertion. In this paper, the robot's mechanical design, system identifications, and the design of its controller are explained. A torque computed controller with gravity compensation and friction models, yielding a 0.678mm RMS position error for the needle tip, was used. A novel method was used for 3D space calibration of the images for detecting the volume of interest in the biopsy procedure by a multipoint crosswire phantom with parallel threads. The calibration technique had a validation RMS error of 0.03mm.
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    Down-conversion emission profile characterisation via camera
    (Optica Publishing Group, 2020-12-14) Kuniyil, Hashir Puthiyapurayil; Durak, Kadir; Electrical & Electronics Engineering; DURAK, Kadir; Kuniyil, Hashir Puthiyapurayil
    We present a method to improve the brightness and collection efficiency of the spontaneous parametric down-conversion source by monitoring the mode shape using camera and correcting it with collection optics.
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    Photon statistics effects on a QRNG of vacuum fluctuations
    (Optica Publishing Group, 2020-09-14) Dandaşi, Abdulrahman; Özel, Helin; Durak, Kadir; Electrical & Electronics Engineering; DURAK, Kadir; Dandaşi, Abdulrahman; Özel, Helin
    Optical scattering enhances randomness characteristics, increases the chaotic behavior of coherent sources, broadens the distribution of photon statistics and makes it super-Poissonian which allows faster sampling compared to Poissonian.
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    PYNQ-based rapid FPGA implementation of quantum key distribution
    (IEEE, 2021) Bilgin, Yiğit; Tesfay, Shewıt Weldu; İpek, Seçkin; Uğurdağ, Hasan Fatih; Durak, Kadir; Gören, S.; Electrical & Electronics Engineering; UĞURDAĞ, Hasan Fatih; DURAK, Kadir; Bilgin, Yiğit
    In this paper, we present a real-time Quantum Key Distribution (QKD) implementation on Field Programmable Gate Arrays (FPGAs) for secure communication. We propose a novel methodology with a Python-based programming interface for rapid development on FPGA. Our methodology revolves three phases of development. In the first phase, a reference model of an entangled photon source and the proposed QKD system are developed in Python. Next, the reference model is passed through a thorough verification phase. In the second phase, the reference model is implemented on the Processing System (PS) part of the FPGA. Finally in the third phase, the computationally intensive part of the QKD architecture is off-loaded on to the Programmable Logic (PL) part of the FPGA for acceleration. We employ PYNQ framework in our QKD development and successfully combine the convenience of Python productivity with FPGA based acceleration.
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    Relaying techniques for free space optical communications
    (Institution of Engineering and Technology, 2019-01-01) Aminikashani, Mohammadreza; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Aminikashani, Mohammadreza
    Despite the major advantages of FSO technology and variety of its application areas, its widespread use has been hampered by its rather disappointing link reliability particularly in long ranges due to atmospheric turbulence-induced fading. Relay-assisted systems have been introduced as an effective method to extend coverage and mitigate the effects of fading in FSO links. In this chapter, we have analyzed and investigated the outage performance of relay-assisted FSO links with AF and DF relays. For serial relaying, it has been demonstrated that the outage probability is minimized when the consecutive nodes are placed equidistant along the path from the source to the destination. For parallel relaying, it has been shown that all of the relays should be located at the same place (along the direct link between the source and the destination) closer to the source and the exact location of this place depends on the system and channel parameters. Multi-hop parallel relaying which is the combined use of serial (multi-hop) and parallel relaying for FSO mesh networks has been also studied. Our analysis yields that multi-hop parallel relaying smartly exploits the distance dependency of the fading variance in FSO systems and bring substantial improvements with respect to standalone uses of multi-hop and parallel relaying. As an alternative way of implementation, all-optical relaying has been also considered. Unlike the earlier relaying schemes, the signals are processed in optical domain and therefore the requirement of OE and EO conversions is avoided. Comparisons between conventional and all-optical relaying demonstrate that the latter presents a favorable trade-off between complexity and performance and can be used as a low-complexity solution.