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Yayın Design trade-offs and considerations for improving the PCB current carrying capacity in high power density power electronics applications(IEEE, 2022-03-24) Büyükdeğirmenci, Veysel Tutku; Kozarva, Ömer F.; Milletsever, Özgür C.; Hava, Ahmet MasumThis paper investigates printed circuit board (PCB) design trade-offs and considerations to maximize the current carrying capacity of traces in PCB-based power electronics applications. Many existing designs rely on methodologies through empirical data presented by the outdated IPC-2152 standard. A design methodology to maximize the utilized PCB area and improve thermal performance is introduced. To assess this methodology, lumped parameter (LP) and finite element (FE) models are developed and computational fluid dynamics (CFD) simulations are carried out. Thermal via placement strategies are investigated and maximum allowable power dissipation on the PCB traces is calculated. Simulations and analyses are experimentally validated on a PCB-based 100kW three-phase three-level inverter. The that results show that the thermal and electrical models discussed in this paper have superior accuracy compared to traditional formulations.Yayın Mixed element wideband microwave amplifier design via simplified real frequency technique(IEEE Computer Society, 2014) Kılınç, Sedat; Köprü, Ramazan; Aksen, Ahmet; Yarman, Bekir Sıddık BinboğaIn this study, we illustrate the design and implementation of a wideband microwave small-signal amplifier composed of mixed elements. The design is based on Simplified Real Frequency Technique (SRFT). A design of low power amplifier circuit is completed and its simulations are performed in success. The circuit is designed with lumped elements, however, some of the lumped elements are converted to distributed elements for their convenience in production. In this way, a mixed element wideband microwave amplifier comprised of input/output matching networks with lumped and distributed elements has been formed. Layout work and also post layout simulation is given with satisfying results.Yayın Transformerless bandpass matching network design for Y-Shaped monopole antenna(IEEE, 2015) Aydın, Çağatay; Atilla, Doğu Çağdaş; Karakuş, Cahit; Köprü, Ramazan; Yarman, Bekir Sıddık BinboğaIn this paper, a transformerless bandpass matching network design procedure is presented. The Real Frequency Techniques are powerful numerical methods to design wideband lossless 2-port networks such that filters and matching networks. In these techniques, the value of the termination resistance of the designed network could not be yielded as 50 ohm by numerical package. Hence, a transformer is also required for 50 ohm termination which is not practical for high frequency applications. Also in this study a novel wideband monopole antenna is presented. The proposed antenna is consisting of two major elements; Y-shaped impedance matching plate and hemi-circular radiator. Moreover Y-shaped impedance matching plate connected to a feeding probe excites the suspended hemi-circular radiator via air gap. and its frequency band is expanded by using transformerless bandpass design procedure.Yayın Adaptive extremum seeking scheme for ABS control(IEEE, 2014) Dinçmen, ErkinA sliding mode based extremum seeking algorithm is applied to the ABS control problem where the optimum slip ratio is searched online for maximum braking force in unknown road conditions. By making the parameter of the search algorithm adaptive, an adaptive extremum seeking scheme is proposed to improve the behavior of the controlled system around the optimum operating point. Simulation study is presented to illustrate the effectiveness of the methodology.Yayın Multiband and concurrent matching network design via brune sections(IEEE, 2017) Yıldız, Serkan; Aksen, Ahmet; Yarman, Bekir Sıddık BinboğaA general multiband matching network design methodology for complex load impedance terminations is presented. In the proposed approach, Real Frequency Techniques (RFT) are used to define and optimize the multiband matching network. In the characterization of the multiband network, multiple notch bands are obtained by the employment of finite transmission zeros (FTZ) in the transfer function. Brune section realization of finite transmission zeros and the associated coupled coil free realizations are discussed. A triple band matching network design for a triple band Sierpinski antenna load is presented to illustrate the performance of the proposed approach.Yayın Annular CMUT arrays for side looking intravascular ultrasound imaging(IEEE, 2007) Zahorian, Jaime; Güldiken, Rasim Oytun; Gürün, Gökçe; Qureshi, Muhammad Shakeel; Balantekin, Müjdat; Değertekin, Fahrettin Levent; Carlier, Stephane; Şişman, Alper; Karaman, MustafaAlthough side looking intravascular ultrasound (SL-IVUS) imaging systems using single element piezoelectric transducers set the resolution standard in the assessment of the extent of coronary artery disease, improvements in transducer performance are needed to perform harmonic imaging and high resolution imaging of vulnerable plaque. With their small channel count; annular arrays exploiting the inherent broad bandwidth of CMUTs and electronic focusing capability of integrated electronics provide a path for desired SL-IVUS imaging catheters. In this paper, we first describe the design, low temperature fabrication of an 8401 mu m diameter, 8 element CMUT annular array. Testing of the individual elements in oil shows a uniform device behavior with 100% fractional bandwidth around 20MHz without including the effects of attenuation and diffraction. We also present linear scan imaging results obtained on wire targets in oil, tissue and tissue mimicking phantoms using both unfocused and dynamically focused transducers. The results for axial and lateral resolution are in agreement predicted by the simulations and show the feasibility of this approach for high resolution SL-IVUS imaging.Yayın NFC Research framework: A literature review and future research directions(Int Business Information Management Assoc-IBIMA, 2010) Özdenizci Köse, Büşra; Aydın, Mehmet Nafiz; Coşkun, Vedat; Ok, KeremNear Field Communication (NFC) is one of the emerging and promising technological developments, provides means to short range contactless communication for mobile phones and other devices alike. NFC has become an attractive research area for many academics due to its exploding growth and its promising applications and related services. An understanding the current status of NFC research area is necessary to maintain the advancement of knowledge in NFC research and to identify the gap between theory and practice. In this paper, we present a literature review on NFC. To facilitate the analysis of the literature, we propose a research framework and organize the NFC literature into four major categories; theory and development, applications and services, infrastructure, ecosystem. This rigorous and holistic literature review with the objective of bringing to the state-of-art in NFC design science research provides advancement of knowledge in NFC research and further research directions.Yayın Volumetric imaging using fan-beam scanning with reduced redundancy 2D arrays(IEEE, 2006) Wygant, Ira; Karaman, Mustafa; Oralkan, Ömer; Khuri-Yakub, Butrus ThomasPhased array processing with a fully populated 2D array produces the best image quality but requires excessive number of active parallel front-end channels. Here we explore four array designs with reduced redundancy in spatial frequency contents. To minimize the number of firings we employ fan-beam processing, where ID arrays are used to insonify 2D planar slices of the volume at successive firing events; echo signals are collected by the receive array elements. The array designs are compared based on simulated point spread functions, frame rate, motion susceptibility, and signal-to-noise ratio.Yayın Design science in NFC research(IEEE, 2010) Özdenizci Köse, Büşra; Aydın, Mehmet Nafiz; Coşkun, Vedat; Ok, KeremNear Field Communication (NFC), as one of the promising technological developments, provides means to short range contactless communication for mobile phones and other devices alike. NFC has become an attractive design science research area for many academicians due to its exploding growth. A better understanding of the current status of NFC research is necessary to identify the gap between theory and practice. In this paper, we evaluate NFC literature from a design science point of view and seven important guidelines of the design science research are employed for evaluating some of the NFC related studies which propose innovative artifacts. Design science perspective of NFC literature gives beneficial guidelines for future studies. This rigorous and holistic literature review with the objective of bringing to the state-of-art in NFC design science research provides advancement of knowledge in NFC research and further research directions.Yayın Mixed-method validation of pedagogical concepts for an intercultural online learning environment: a case study(Assoc Computing Machinery, 2007) Law, Effie Lai-Chong; Nguyen-Ngoc, Anh Vu; Kuru, SelahattinThe rise of social software poses the challenges to the design and evaluation of a pedagogically sound online learning environment (OLE). Our OLE addresses these challenges by the integration of three pedagogical concepts - cross-cultural collaboration, self-directed learning and social networking - with the aim to advance participants' competencies and by mixed-method approaches to evaluating the complex situations. A validation trial involving four European countries was conducted. Groups of students co-created a questionnaire, which was assessed to provide an indicator of task performance. Multi-source (surveys, blogs, emails, diaries, chats, videoconference, and interviews) and multi-perspective data (facilitators, students, researchers) were studied with social network analysis, content analysis and conversation analysis. Several a posteriori research questions are addressed.
