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Publication Metadata only An innovative computational model of the thermal comfort conditions in city / inter-city buses(2000) Körbahti, Banu; Kucur, Murad; Kaykayoǧlu, C. Ruhi; Körbahti, Banu, Department of Mechanical Engineering, Istanbul Üniversitesi, Istanbul, Turkey; Kucur, Murad, Department of Mechanical Engineering, Istanbul Üniversitesi, Istanbul, Turkey; Kaykayoǧlu, C. Ruhi, Faculty of Engineering, Bahçeşehir Üniversitesi, Istanbul, TurkeyMeeting customer needs in a limited time schedule always require fast, cheap and highly accurate modelling tools in automotive industry. Moreover, in order to be competitive in international markets, companies try to simulate the climate conditions of the customer' s home country at their research and development laboratories. The climate and the seasonal outdoor conditions are the main input data for thermal comfort design. Since it is not practical and cheap to perform experiments in real conditions, companies prefer to use computer aided engineering design tools to simulate the heating and cooling scenories inside the bus cabins. In this investigation, the authors propose an efficient computer algoritm for the fast calculation of the temperature field inside a bus cabin based on a lumped parameter model. It is demonstrated that the algoritm is numerically capable of producing results in agreement with the experimental data. © ECCOMAS. © 2014 Elsevier B.V., All rights reserved.Publication Metadata only Reliability analysis in N-version programming with dependent failures(2001) Ege, Mustafa; Eyler, M. Akif; Karakaş, M. Ümit; Ege, Mustafa, Department of Computer Engineering, Hacettepe Üniversitesi, Ankara, Turkey; Eyler, M. Akif, Department of Computer Engineering, Marmara Üniversitesi, Istanbul, Turkey; Karakaş, M. Ümit, Department of Computer Engineering, Bahçeşehir Üniversitesi, Istanbul, TurkeyIn fault-tolerant software, to enhance the reliability, one of the major approaches is N-version programming. The modeling studies provided in literature help us to understand under which conditions these approaches increase the software reliability. In this paper, the models given in literature for N-version programming are reviewed. We discuss the deficiency in one of these models trying to improve it to agree with another independent reliability model. Furthermore, we examine how we can combine the dependency concept with the independent reliability model and the subject of how we can extend it for N value. By taking into consideration the dependent failure behavior, a dependent failure parameter is introduced to the reliability model in case the events are /spl alpha/-dependent. Here, /spl alpha/ measures the similarity percentage of the input sets on which each pair of versions fail. © 2001 IEEE. © 2013 Elsevier B.V., All rights reserved.Publication Metadata only State space method for reducing phase fluctuations for the radio waves travelling through the ionosphere at 26 MHz(Institute of Electrical and Electronics Engineers Inc., 2003) Okatan, Ali Ertan; Kurnaz, S.; Ince, F.; Onbasioglu, S.; Okatan, Ali Ertan, Department of Computer Engineering, Bahçeşehir Üniversitesi, Istanbul, TurkeyIn this work one of the most important problems in the radio astronomy has been attacked. In radio astronomy antenna arrays are used with very long baselines in order to obtain good angular resolutions. For the baseline of 3000 km the two element array gives an effect of a parabolic antenna as if it has 3 000 k m radius. The antennas see different parts of the Ionosphere because of the large distance between the antennas. These deferent regions seen by the two antennas have different random dynamic structures with a small correlation of these dynamic time varying structures. These different changes in two different regions of the Ionosphere cause different random phase changes of received waves by the antennas. The effects are large for the frequencies at 26 MHz regions. The observations are important at this frequency region for different reasons. Because of the random phase fluctuations of the received waves, random phase drift of the local oscillators and the limited observation time, the correlation between the signals obtained from the receivers is below the detection level. Therefore, detection becomes even impossible. In this work, the differential ionospheric. phase error is modeled as quasi-sinusoidal exponential phase because of the periodic structure of ionospheric irregularity blobs. The differential oscillator drift is modeled as a linear change with a random slope. Finally, the total differential phase error is expressed as a matrix equation with approximate parameters. Applying the recursive Kalman Filter algorithm to the matrix equation the m e phase is estimafed. With the new phase, the correlation function is reconstructed. This process improved the S/N ratio in great extend. The method has been applied to the radio star 3C144 and very good results have been obtained. Because of improvements in the processing speeds of the computers lately, the method seems to be valuable. © 2015 Elsevier B.V., All rights reserved.Publication Metadata only A multi-window fractional evolutionary spectral analysis(Institute of Electrical and Electronics Engineers Inc., 2003) Cekic, Yalcin; Akan, Aydin I.; Cekic, Yalcin, Department of Electrical Engineering, Bahçeşehir Üniversitesi, Istanbul, Turkey; Akan, Aydin I., Department of Electrical Engineering, Istanbul Üniversitesi, Istanbul, TurkeyIn this work, we present a multiple window Evolutionary Spectral analysis on a non-rectangular time-frequency lattice based on a discrete fractional Gabor expansion. The traditional Gabor expansion uses a fixed, and rectangular time-frequency plane tiling. Many of the practical signals such as speech, music, etc., require a more flexible, non-rectangular time-frequency lattice for a compact representation. The proposed method uses a set of basis functions that are related to the fractional Fourier basis and generate a parallelogram-shaped tiling. Simulation results are given to illustrate the performance of our algorithm. © 2022 Elsevier B.V., All rights reserved.Publication Metadata only Trellis decoding of some decomposable codes(Institute of Electrical and Electronics Engineers Inc., 2003) Altay, Gökmen; Yalçin, Şenay; Uçan, Osman Nuri; Kurnaz, S.; Ince, F.; Onbasioglu, S.; Altay, Gökmen, Department of Electrical and Electronic Engineering, Bahçeşehir Üniversitesi, Istanbul, Turkey; Yalçin, Şenay, Department of Mathematics, Bahçeşehir Üniversitesi, Istanbul, Turkey; Uçan, Osman Nuri, Department of Electrical and Electronic Engineering, Istanbul Üniversitesi, Istanbul, TurkeyThis paper presents a maximum likelihood identical minimal trellises of d4SP codes and it (ML) soft decision decoding scheme to implement Viterbi significantly reduces the decoding complexity by Algorithm for some constructed decomposable codes of performing iterations for each sub-trellis. Bit error rate Hamming distance four and show that the decoding performances of some d4SP codes are obtained in additive complexity is simple, hence, it may be employed in trellis- white Gaussian channel (AWGN) and also complexity of based decoders. A bit error rate performance of some decoding processes is analyzed in detail. Decomposable codes that were obtained employing the technique in AWGN channel are also presented. © 2015 Elsevier B.V., All rights reserved.Publication Metadata only Micro-controller based vehicle tracing system via use of GPS AND GSM(Institute of Electrical and Electronics Engineers Inc., 2003) Okatan, Ali Ertan; Salih, Ali; Akpolat, Çaʇatay; Çelik, Koray; Kurnaz, S.; Ince, F.; Onbasioglu, S.; Okatan, Ali Ertan, Department of Computer Engineering, Bahçeşehir Üniversitesi, Istanbul, Turkey; Salih, Ali, Department of Computer Engineering, Bahçeşehir Üniversitesi, Istanbul, Turkey; Akpolat, Çaʇatay, Department of Computer Engineering, Bahçeşehir Üniversitesi, Istanbul, Turkey; Çelik, Koray, Department of Computer Engineering, Bahçeşehir Üniversitesi, Istanbul, TurkeyIn this work of novel micro-controller based vehicle tracing system has been designed and its software has been developed. By this system, location and the speed of a vehicle are monitored and they can be reported to a base station if a defined event stored in the program or a query from base station takes place. © 2015 Elsevier B.V., All rights reserved.Publication Metadata only Investigation the level of neural synchronization by using global field synchronization method in Obsessive Compulsive Disorder, Obsesif kompulsif bozuklukta nöral senkronizasyon düzeyinin global alan senkronizasyon yöntemi ile ̄ncelenmesi(Institute of Electrical and Electronics Engineers Inc., 2003) Özçoban, Mehmet Akif; Kara, S.; Tan, Oguz; Aydın, Serap; Özçoban, Mehmet Akif, Elektronik Teknolojisi Programi, Gedik Üniversitesi, Istanbul, Turkey; Kara, S., Fatih Üniversitesi, Istanbul, Turkey; Tan, Oguz, Üsküdar Üniversitesi, Istanbul, Turkey; Aydın, Serap, Bahçeşehir Üniversitesi, Istanbul, TurkeyObsessive Compulsive Disorder (OCD) is a neuropsychiatric brain disorder disease and diagnosis, treatment process of the disease is used EEG analysis. Recent studies suggested that the OCD is caused by dysfunction in brain's frontal lobe. The GFS that was developed as a novel synchronization criteria, computes phase difference between neural oscillations in the brain. Studies were published that indicates fall of GFS values. In this study, it was investigated how OCD effect phase difference between neuronal oscillations. For this purpose, results of the GFS method was applied to 19 channels EEG, indicates OCD decrease of neural synchronization in brain's frontal lobe at Delta and Beta 3 frequency bands. © 2015 Elsevier B.V., All rights reserved.Publication Metadata only Motion control via telecommunication networks: Random time delays and a simple stability design(IFAC Secretariat Schlossplatz 12 A-2361 Laxenburg A-2361, 2003) Okatan, Ali Ertan; Dimirovski, Geogi M.; Okatan, Ali Ertan, Department of Computer Engineering, Bahçeşehir Üniversitesi, Istanbul, Turkey; Dimirovski, Geogi M., Department of Computer Engineering, Doğuş Üniversitesi Istanbul, Istanbul, Turkey, Faculty of Electrical Engineering, Ss. Cyril and Methodius University in Skopje, Skopje, North MacedoniaMotion control and navigation via telecommunications networks as well as the control of other dynamical systems recently again came in the focus by a number of authors world-wide. It has been subject to extensive investigation because of remote motion control applications, and also because of the impact of random time delays caused by telecommunication networking, e.g., Internet. The most essential phenomenon in implementing remote control via Internet networking is that of a random, rime varying pure time delay. In turn, this phenomenon gives rise to the issue of closed-loop stability which may cause control performance deterioration, and even instability brake down of such control systems. Within the limitations of using linear models of the dynamics of controlled object - remote motion control process m open-loop system, a tbrough design analysis is feasible and has been elaborated m the course of our research. In order to ensure the system stability, the maximum expected time-delay phenomenon must be observed at design stage of the control system Hence the main design conclusion is to ensure that system parameters be adjusted according to the maximum expected delay distributions always. © 2019 Elsevier B.V., All rights reserved.Publication Metadata only Neural network based motor bearing fault detection(2004) Eren, Levent; Karahoca, Adem; Devaney, Michael Joseph; Demidenko, S.; Ottoboni, R.; Petri, D.; Piuri, V.; Weng, D.C.T.; Eren, Levent, Department of Electrical Engineering, Bahçeşehir Üniversitesi, Istanbul, Turkey; Karahoca, Adem, Department of Computer Engineering, Bahçeşehir Üniversitesi, Istanbul, Turkey; Devaney, Michael Joseph, College of Engineering, Columbia, United StatesBearing faults are the biggest single cause of motor failures. The bearing defects induce vibration resulting in the modulation of the stator current. The stator current can be analyzed via wavelet packet decomposition to detect bearing defects. This method enables the analysis of frequency bands that can accommodate the rotational speed dependence of the bearing defect frequencies. In this study, Radial Basis Function Neural Networks are used to improve bearing fault detection procedure. © 2011 Elsevier B.V., All rights reserved.Publication Metadata only Harmonic analysis via wavelet packet decomposition using special elliptic half-band filters(2004) Eren, Levent; Ünal, Mehmet; Devaney, Michael Joseph; Demidenko, S.; Ottoboni, R.; Petri, D.; Piuri, V.; Weng, D.C.T.; Eren, Levent, Department of Electrical Engineering, Bahçeşehir Üniversitesi, Istanbul, Turkey; Ünal, Mehmet, Department of Mathematics, Bahçeşehir Üniversitesi, Istanbul, Turkey; Devaney, Michael Joseph, College of Engineering, Columbia, United StatesThe Fast Fourier Transform is the most widely used power system harmonic analysis tool in real time power metering due to its computational efficiency. Recently, an alternate method, wavelet packet decomposition, has been applied to power system signals to meter voltage and current harmonics. Although the new method provides better analysis, the computational complexity of wavelet packet decomposition places a limitation on its use in real time metering. This paper proposes the use of all-pass implemented half-band elliptic IIR filters in the wavelet packet decomposition of power system signals. The proposed implementation reduces the computational complexity to levels comparable to Fast Fourier Transform. © 2011 Elsevier B.V., All rights reserved.