Browsing Fakülteler / Faculties by Issue Date

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  • VLSI implementation of GRBF (Gaussian Radial Basis Function) networks 

    Authors:Çevikbaş, I. Can; Öǧrenci, Arif Selçuk; Dündar, Günhan; Balkır, Sina
    Publisher and Date:(IEEE, 2000)
    A GRBF network is designed for VLSI implementation. Building blocks of the network consist mainly of analog circuits: op-amp multiplier multiplying DAC (digital to analog converter) floating resistor summer and exponentiator. Parameters of the network (center width of the Gaussian function and output layer weights) are represented digitally for convenient interfacing. It is shown that individual GRBF units allow independent tuning of center width and amplitude. Several network structures are ...

  • A synthesis tool for the multiplierless realization of FIR-based multirate DSP systems 

    Authors:Yurdakul, Arda
    Publisher and Date:(IEEE, 2000)
    In this study a synthesis tool using a novel multirate folding technique which handles each FIR filter in a multirate DSP system as a single node is developed. A new architecture is presented for the multiplierless realization of a fold of multirate FIR filters. This synthesizer fully exploits the redundancies (i.e. `idle' and `missing' cycles) and common terms in multirate systems without sacrificing from overall system quality to produce multiplierless multirate systems. It also enables the usage ...

  • Parameter quantization effects in Gaussian potential function neural networks 

    Authors:Karakuş, Erkan; Öǧrenci, Arif Selçuk; Dündar, Günhan
    Publisher and Date:(World Scientific and Engineering Academy and Society, 2001)
    In hardware implementations of Gaussian Potential Function Neural Networks (GPFNN) deviation from ideal network parameters is inevitable because of the techniques used for parameter storage and implementation of the functions electronically resulting in loss of accuracy. This loss in accuracy can be represented by quantization of the network parameters. In order to predict this effect theoretical approaches are proposed. One-input one-output GPFNN with one hidden layer have been trained as function ...

  • Fault-tolerant training of neural networks in the presence of MOS transistor mismatches 

    Authors:Öǧrenci, Arif Selçuk; Dündar, Günhan; Balkır, Sina
    Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2001)
    Analog techniques are desirable for hardware implementation of neural networks due to their numerous advantages such as small size low power and high speed. However these advantages are often offset by the difficulty in the training of analog neural network circuitry. In particular training of the circuitry by software based on hardware models is impaired by statistical variations in the integrated circuit production process resulting in performance degradation. In this paper a new paradigm of ...

  • The stability constants of the rare earth complexes with trimetaphosphoric acid 

    Authors:Şungur, Şana Kutun
    Publisher and Date:(Soc Chimica Italiana, 2001)
    The stability constants of the complexes formed between the rare earth metal ions and the anion of trimetaphosphoric acid have been determined at a temperature of 20 degreesC and an ionic strength of mu =0.1 by the ion-exchange equilibrium method. The investigations indicate that stabilities of complexes increased from La to Lu.The highest and the lowest stability constant values (beta) were found to be 7.76 and 3.82 for Lu3+ and La3+ respectively.

  • Yeni Keynesci Yaklaşımda Ücret ve İstihdam 

    Authors:Bilgin, Mehmet Hüseyin
    Publisher and Date:(İstanbul Üniversitesi, 2002)
    The purpose of this paper is to explore the new Keynesian approach on wages and employment relationship. According to new Keynesian school, market clearing mechanism does not exist due to rigidities and stickiness. This situation leads involuntary unemployment. In new Keynesian theory, there are three theories to explain wage rigidities and involuntary unemployment. This paper analyzes these theories in detail and discusses the new Keynesian assumptions from the perspective of Turkish labor market.

  • A broadband microwave amplifier design by means of immittance based data modelling tool 

    Authors:Kilinç, Ali; Pinarbaşi, Haci; Şengül, Metin Y.; Yarman, Sıddık Binboğa
    Publisher and Date:(IEEE, 2002)
    In this paper a practical broadband microwave amplifier design algorithm is introduced utilizing the immittance data-modelling tool. In the course of design first the optimum input and output terminations for the active device are produced employing the real frequency technique. Then these terminations are modelled utilizing the new immittance-modelling tool to synthesize the front-end and back-end matching networks. An example is included to exhibit the implementation of the proposed design ...

  • Edge detection using steerable filters and CNN 

    Authors:Özmen, Atilla; Akman, Emir Tufan
    Publisher and Date:(European Signal Processing Conference EUSIPCO, 2002)
    This paper proposes a new approach for edge detection using steerable filters and cellular neural networks (CNNs) where the former yields the local direction of dominant orientation and the latter provides iterative filtering. For this purpose steerable filter coefficients are used in CNN as a B template. The results are compared to the results where only CNN or steerable filters are used. As a result of this study the performance of the system can be improved since iterative filtering property ...

  • Attitudes towards knowledge management in Turkish companies 

    Authors:Üçdal, Erol; Güzey, Yildiz Y.
    Publisher and Date:(2002)
    Attitudes towards knowledge management in Turkish companies are discussed. More and more companies in Turkish economy are allocating responsibility and a budget for knowledge management. Analysis show that the acts of successful knowledge management strategies brings new types of working giving people the chance to invest in knowledge maintaining the culture change and rewarding employees with new incentive schemes.

  • Trust confidence and e-commerce in cyberspace 

    Authors:Güzey, Yildiz Y.
    Publisher and Date:(2002)
    The trust confidence and e-commerce issues in cyberspace are discussed. Development of commercial activities in the cyberspace hinges on assuring consumers and businesses that their use of network services were safe secure and reliable. E-commerce requires trust across the spectrum of users and providers of services and goods. The cyberspace will never be completely secure reliable trustworthy and involves a calculated risk.

  • Jonson and the alchemical economy of desire: creation defacement and castration in the 'Alchemist' 

    Authors:Meskill, Sermin Lynn
    Publisher and Date:(Univ Paul Valery, 2002)
    Behind images of Ben Jonson as the virtuous centred stoic writer lie the traces of a morbid fear concerning the fate of the poet's creation and name. The Jonsonian oeuvre reveals a fear of the ultimate defacement and effacement of the writer's ephemeral text. A prophylactic strategy of auto-critique as well as borrowing and even plagiarism from established literary sources point to the desire to control the critical reception of the writer's works and guarantee the terms of his own posterity. In ...

  • Metalization of polymer beads via polymer-supported hydrazines as reducing agents 

    Authors:Bıçak, Niyazi; Şungur, Şana Kutun; Tan, Nükhet; Bensebaa, Farid; Deslandes, Yves
    Publisher and Date:(John Wiley & Sons Inc, 2002)
    A new method for depositing metal onto a polymer surface has been developed in which the metal coating of polymer beads is performed with hydrazine functions as reducing agents on the surface of the polymer itself. In this study glycidyl methacrylate-methyl methaerylate-divinyl benzene terpolymer was prepared as spherical beads with a suspension polymerization methodology. Beads of the polymer sample (210-420-mum fraction) containing 3.4 mmol g(-1) epoxy were treated with an excess of hydrazinium ...

  • Cosmic ray intensity variation during a CME 

    Authors:Kandemir, Gulcın; Geçkinli, Melih; Fırat, Coşkun; Yılmaz, Melek; Özuğur, B
    Publisher and Date:(Pergamon-Elsevier Science Ltd, 2002)
    The June 6 2000 coronal mass ejection was an exceptional full halo which made it possible to measure cosmic ray (CR) decrease with a simple experimental set-up. Variation in the local secondary cosmic ray density has been investigated by means of gamma rays. The experiment site was located in Istanbul (41.1N 29.0E). CR electrons and slow gamma rays have been eliminated. The CR density has dropped drastically starting on June 8 2000. The counts have been compared with the pre-shock levels and some ...

  • Chelate extraction of transition metal ions by ethylene diamine diacetic acid with n-substituted octadecyl groups 

    Authors:Bıçak, Niyazi; Şungur, Şana Kutun; Tan, Nükhet; Gazi, Mustafa
    Publisher and Date:(Taylor & Francis Inc, 2002)
    An organic-soluble chelating agent NN'-di-n-octadecyl ethylenediamine-NN'-diacetic acid (DOED) has been synthesized in two steps by (i) condensation of dibromoethane with 1-amino octadecane (octadecylamine) and (ii) subsequent reaction with sodium chloro acetate in alcohol-water mixture. The chelating agent in 2-ethylhexanol-cyclohexanol (1:1) solutions shows extremely high chelating ability for Ni(II) Co(II) Cu(II) Fe(111) Cr(III) and Cd(II) ions in neutral aqueous solutions. Extractions take ...

  • Yönlendirmeli Filtreler Yardımıyla Konya Bölgesi Civarındaki Gömülü Fayların Tespiti 

    Authors:Özmen, Atilla; Uçan, Osman N.; Albora, A. Muhittin
    Publisher and Date:(Doğuş Üniversitesi, 2003)
    Bu makalede, yönlendirmeli filtreler jeofizik verilerin değerlendirilmesinde kullanılmışlardır. Yönlendirmeli filtreler belirli bir doğrultuda band geçiren filtrelerdir. Yönlendirmeli filtreler de, giriş görüntüsündeki farklı yönlerdeki kenarların elde edilmesi için, görüntü ilk önce farklı yönlere sahip temel filtrelerden geçirilir ve daha sonra yönelim alt bandlarına ayrılır. Bu çalışmada, yönlendirmeli filtrelerin başarımını görebilmek için, çeşitli açılara sahip sentetik datalar ele alınmış ...

  • Zero-crossing based demodulation of minimum shift keying 

    Authors:Kalkan, Mine; Kerestecioǧlu, Feza
    Publisher and Date:(2003)
    Minimum shift keying (MSK) modulation has features such as constant envelope compact spectrum and good error performance which are all desirable in many digital applications including mobile radio. Numerous receiver structures to demodulate MSK have been suggested such as correlation receivers differential detectors and frequency discriminators MSK is a form of biphase keying and can be detected by a zero-crossing based phase demodulator which gives near optimum performance. In this paper the bit ...

  • Sliding mode controller solution for the shallow submerged operation ok a submarine 

    Authors:Demirci, Ufuk; Kerestecioǧlu, Feza
    Publisher and Date:(IFAC Secretariat, 2003)
    In this paper a submarine controller is presented which can accommodate the sea wave effects on a submarine a(shallow water operation. Sliding mode method is implemented in a way that the robustness of the controller increased with respect to disturbance distribution vector in order to perform the depth control of a shallow submerged submarine under sea wave disturbances. Designed controller kept the submarine performance within acceptable limits. Copyright © 2003 IFAC.

  • Active reconfigurable control of a submarine with indirect adaptive control 

    Authors:Demirci, Ufuk; Kerestecioǧlu, Feza
    Publisher and Date:(2003)
    An indirect adaptive controller is designed for submersibles. The design is developed using a linearized MIMO model of a submarine. Standard recursive least squares estimation method is used to estimate the parameters. Depth and pitch angle of the submarine is controlled by means of the well-known indirect self-tuning method. In case of a system fault estimated parameters of the submarine model have been used to update the controller coefficients.

  • Selective liquid-liquid extraction of mercuric ions by octyl methane sulfonamide 

    Authors:Bıçak, Niyazi; Sungur, Sana; Gazi, Mustafa; Tan, Nükhet
    Publisher and Date:(Marcel Dekker Inc, 2003)
    N-octyl methane sulfonamide (OMSA) has been demonstrated to be a very efficient reagent for selective extraction of Hg(II) ions from aqueous solutions. The extraction bases on rapid reaction of OMSA with Hg(II) ions yielding mono and disulfonamido mercury compounds in ordinary conditions. Solubility of OMSA and its mercury compounds in 2-ethyl hexanol provide a clear-cut phase separation in the extraction. The solution of OMSA in 2-ethyl hexanol (0.4 mol L-1) is able to extract 82.2% of mercuric-acetate ...

  • Nonuniform sampling for detection of abrupt changes 

    Authors:Kerestecioǧlu, Feza; Tokat, Sezai
    Publisher and Date:(Birkhauser Boston Inc, 2003)
    In this work detection of abrupt changes in continuous-time linear stochastic systems and selection of the sampling interval to improve the detection performance are considered. Cost functions are proposed to optimize both uniform and nonuniform sampling intervals for the well-known cumulative sum algorithm. Some iterative techniques are presented to make online optimization computationally feasible. It is shown that considerable improvement in the detection performance can be obtained by using ...