Elektrik - Elektronik Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/202

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  • Review
    Aerial Swarms: Recent Applications and Challenges
    (Springer, 2021) Mohamed Abdelkader; Samet Güler
    Purpose of review: Currently, there is a large body of research on multi-agent systems addressing their different system theoretic aspects. Aerial swarms as one type of multi-agent robotic systems have recently gained huge interest due to their potential applications. However, aerial robot groups are complex multi-disciplinary systems and usually research works focus on specific system aspects for particular applications. The purpose of this review is to provide an overview of the main motivating applications that drive the majority of research works in this field, and summarize fundamental and common algorithmic components required for their development._x000D_ _x000D_ Recent findings: Most system demonstrations of current aerial swarms are based on simulations, some have shown experiments using few 10 s of robots in controlled indoor environment, and limited number of works have reported outdoor experiments with small number of autonomous aerial vehicles. This indicates scalability issues of current swarm systems in real world environments. This is mainly due to the limited confidence on the individual robot's localization, swarm-level relative localization, and the rate of exchanged information between the robots that is required for planning safe coordinated motions._x000D_ _x000D_ Summary: This paper summarizes the main motivating aerial swarm applications and the associated research works. In addition, the main research findings of the core elements of any aerial swarm system, state estimation and mission planning, are also presented. Finally, this paper presents a proposed abstraction of an aerial swarm system architecture that can help developers understand the main required modules of such systems.
  • Article
    Citation - Scopus: 1
    AlN Piezoelectric Quad-Actuators for 2D Optical Micro Scanning
    (Taylor & Francis Ltd, 2022) Hah, Dooyoung
    Piezoelectric actuation has been one of the frequent choices for optical micro scanning. In most of the cases, lead zirconate titanate (PZT) has been used as the piezoelectric material. However, PZT has a potential issue in biomedical applications due to the content of lead. For this, AlN can be used as an alternative. The main drawback of AlN is its low piezoelectric coefficients. In order to overcome such a drawback, this paper presents a novel actuator configuration, designed for a quasi-static operation mode. Quad-actuators and meander-shaped hinges are the essence of the proposed actuator configuration. Numerical simulation study is carried out to prove the concept of the device. The study also shows that the proposed scanner can have the optical scan angle of 9 degree at a quasi-static mode. Two different scan modes, a raster-like mode and a Lissajous mode are tested, demonstrating the two-dimensional scanning capability of the device.
  • Article
    Citation - WoS: 44
    Citation - Scopus: 46
    Highly Efficient Cd-Free Alloyed Core/Shell Quantum Dots With Optimized Precursor Concentrations
    (Amer Chemical Soc, 2016) Altintas, Yemliha; Talpur, Mohammad Younis; Unlu, Miray; Mutlugun, Evren
    The chemical composition, the emission spectral bandwidth, and photoluminescence quantum yield of a semiconductor quantum dot (QD) play an important role in the assessment of the performance of the applications related to the quantum dots. Quantum dots based on environmentally friendly compositions with high optical performance have been in demand for high-end technological applications. In this work, we propose and demonstrate a detailed synthesis approach for environmentally friendly and highly efficient InPZnS alloy/ZnS shell quantum dots. Following a systematic study of the ratio and type of the precursors involved, we achieved alloyed core shell InPZnS/ZnS QDs with tunable emission across the visible spectrum, having a record quantum efficiency up to 78% along with a full width at half-maximum as narrow as 45 nm. The effect of the systematic shell growth has been further investigated using time-resolved photoluminescence characterizations along with the observation of the suppression of the nonradiative decay channels, with the photoluminescence lifetime prolonged from 20.3 to 50.4 ns. The development of highly efficient and environmentally friendly QDs will pave the way for robust, sustainable optoelectronic applications.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Excitonic Interaction Amongst InP/ZnS Salt Pellets
    (Royal Soc Chemistry, 2017) Altintas, Yemliha; Yazici, Ahmet Faruk; Unlu, Miray; Dadi, Seyma; Genc, Sinan; Mutlugun, Evren; Faruk Yazici, Ahmet
    Salt matrix has recently been introduced as a promising robust platform for embedding colloidal quantum dots to provide them with photo stability for versatile applications. This work demonstrates the excitonic interaction amongst high efficiency colloidal InP/ZnS quantum dots embedded in a KCl salt matrix. By varying the donor acceptor ratio within the solid platform, 65% Forster Resonance Energy Transfer (FRET) efficiency was attained. Optimizing the donor : acceptor ratio, we demonstrated the first FRET-enabled Cd-free pellets for white light generation possessing a color rendering index (CRI) of 84.7, correlated color temperature (CCT) of 5347.5 K, and a high luminous efficacy of optical radiation value (LER) of 324.3 lm/W-opt. Our study of excitonic interactions within quantum dot-loaded salt matrices will open new possibilities for future versatile optoelectronic applications.