Now showing items 210-229 of 280

  • Rapidly Varying Sparse Channel Tracking with Hybrid Kalman-OMP Algorithm 

    It is expected from future communication standards that channel estimation algorithms should be able to operate over very fast varying frequency selective channel models. Therefore in this study autoregressive (AR) modeled fast varying channel has been considered and tracked with Kalman filter over one orthogonal frequency division multiplexing (OFDM) symbol. Channel sparsity is exploited which decreases the complexity requirements of the Kalman algorithm. Since Kalman filter is not directly ...

  • Real frequency design of Pi and T matching networks with complex terminations 

    In this paper real frequency design of Pi and T matching networks with complex terminations is studied. Generally the generator and load termination impedances are given as measurement values. So they can be regarded as a resistor and a reactive element connected in series. To be able to design a Pi network this series impedance models must be transformed to parallel models. But for T network designs the assumed series models can be utilized there is no need a transformation process. Then Pi or T ...

  • Real Frequency Design of Pi and T Matching Networks with Complex Terminations 

    Authors:Şengül, Metin Y.; Yeşilyurt, Gökmen
    Publisher and Date:(IEEE, 2017)
    In this paper real frequency design of Pi and T matching networks with complex terminations is studied. Generally the generator and load termination impedances are given as measurement values. So they can be regarded as a resistor and a reactive element connected in series. To be able to design a Pi network this series impedance models must be transformed to parallel models. But for T network designs the assumed series models can be utilized there is no need a transformation process. Then Pi or T ...

  • Realization of ideal filter characteristics via genetic algorithm 

    Authors:Şengül, Metin Y.; Özmen, Atilla
    Publisher and Date:(2011)
    In this paper realization of ideal filter characteristics via genetic algorithm has been studied. The filter is defined as a lossless two-port terminated normalized source and load resistances and the coefficients of its describing scattering polynomials have been calculated via genetic algorithm. An element value table has been given for a low-pass normalized prototype filter containing only one element to ten elements. © 2011 Chamber of Turkish Electric.

  • Reflectance-based Foster impedance data modeling 

    Authors:Şengül, Metin Y.
    Publisher and Date:(Fachverlag Schiele Schon, 2007)
    A reflectance-based method is presented to model a set of given Foster impedance data as a lossless singly terminated two-port consisting of lumped-elements in short or open termination. The basis of the new method rests on the interpolation of the given data as a realizable bounded-real (BR) reflection function. The desired circuit model is obtained by synthesizing this function. An algorithm to generate the circuit model is presented and an example is included which illustrates the utilization ...

  • Reflection Modeling Based Broadband Matching Network Design 

    Authors:Şengül, Metin Y.
    Publisher and Date:(Walter De Gruyter, 2017)
    In this paper a new broadband matching network design approach based on reflection modeling is proposed which has two parts: impedance data generation and modeling. In the approach firstly the output impedance data of the matching network is obtained to get the desired flat transducer power gain in the passband. Next the output reflection data are calculated using the obtained impedance data then they are modeled as a bounded real function. Then this function is synthesized and the desired lossless ...

  • Relativistic antihydrogen production by pair production with positron capture 

    Authors:Şengül, Metin Y.; Guclu, Mehmet C.
    Publisher and Date:(Elsevier Science Bv, 2012)
    Antihydrogen atoms may rarely be produced by the collision of antiprotons with ions. At relativistic velocities the antiproton may pass around the Coulomb field of the nucleus and the electron-positron pairs can be produced electromagnetically. After this pair production not so often positron can be captured by the antiproton and as a result antihydrogen atoms may be produced. In this work we have calculated the antihydrogen production cross section in the framework of perturbation theory by ...

  • Relay-Aided Secure Broadcasting for VLC 

    Authors:Arafa, Ahmed; Panayirci, Erdal; Poor, H. Vincent
    Publisher and Date:(IEEE, 2018)
    A visible light communication (VLC) broadcast channel is considered in which a transmitter communicates with two receivers in the presence of an external eavesdropper. Trusted cooperative half-duplex relays are deployed to aid with securing the transmitted data. Transmission is amplitude-constrained to maintain operation within the light emitting diodes (LEDs) dynamic range. Achievable secrecy rate regions are derived under such amplitude constraints for this multi receiver wiretap channel first ...

  • Relay-aided secure broadcasting for VLC 

    A visible light communication (VLC) broadcast channel is considered in which a transmitter communicates with two receivers in the presence of an external eavesdropper. Trusted cooperative half-duplex relays are deployed to aid with securing the transmitted data. Transmission is amplitude-constrained to maintain operation within the light emitting diodes (LEDs) dynamic range. Achievable secrecy rate regions are derived under such amplitude constraints for this multi receiver wiretap channel first ...

  • Reliable Two-Path Successive Relaying 

    Emerging two-path successive relaying protocols generally rely on error-free source-relay channels and/or interference-free inter-relay channels to achieve high-rate and full-diversity. In this paper by removing these optimistic assumptions a novel two-path successive relaying scheme that benefits from relay selection and distributed space-time block coding (STBC) and transfers the data from the source to the destination via relays in a reliable fashion is proposed. The proposed scheme can achieve ...

  • Reliable two-path successive relaying 

    Emerging two-path successive relaying protocols generally rely on error-free source-relay channels and/or interference-free inter-relay channels to achieve high-rate and full-diversity. In this paper by removing these optimistic assumptions a novel two-path successive relaying scheme that benefits from relay selection and distributed space-time block coding (STBC) and transfers the data from the source to the destination via relays in a reliable fashion is proposed. The proposed scheme can achieve ...

  • RGB color based occupancy rate detection of indoor spaces [RGB renk tabanlı kapalı mekanların doluluk oranının belirlenmesi] 

    In this study a system has been developed to detect the human density of indoor spaces such as libraries banks shopping malls. The RGB images used in this work was obtained from the real-life space. First and second order color moments were used as feature extractor. © 2018 IEEE.

  • Routing performance analysis of opportunistic networks with flooding and partial flooding methods [Fırsatçı aǧlarda taşırma ve kısmi taşırma yöntemleriyle yönlendirme performans analizi] 

    Opportunistic networks is one of the fast developing research areas in mobile communications. Under opportunistic networks mobile nodes try to communicate with other nodes without any prior information and knowledge about the network topology. Furthermore network topologies are dynamic and can rapidly change. In addition communication under opportunistic networks is erratic thus routes between a source node and a destination node sometimes might not exist. These issues would make classical routing ...

  • Routing with (p-percent) partial flooding for opportunistic networks 

    Opportunistic networks are one of the fast developing research areas in mobile communications. Under opportunistic networks mobile nodes try to communicate with other nodes without any prior information and knowledge about the network topology. Furthermore the network topologies are dynamic and can rapidly change. In addition communication under opportunistic networks can be erratic thus routes between a source node and a destination node sometimes might not exist. These issues would make traditonal ...

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

    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 ...

  • Semiblind joint channel estimation and equalization for OFDM systems in rapidly varying channels 

    We describe a new joint iterative channel estimation and equalization algorithm for joint channel estimation and data detection for orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency selective and rapidly timevarying channels. The algorithm is based on the expectation maximization-maximum a posteriori (EM-MAP) technique which is very suitable for the multicarrier signal formats. The algorithm leads to a receiver structure that yields the equalized output using ...

  • Shifted-modified Chebyshev filters 

    This paper introduces a new type of filter approximation method that utilizes shifted-modified Chebyshev filters. Construction of the new filters involves the use of shifted-modified Chebyshev polynomials that are formed using the roots of conventional Chebyshev polynomials. The study also includes 2 tables containing the shifted-modified Chebyshev polynomials and the normalized element values for the low-pass prototype filters up to degree 6. The transducer power gain group delay and impulse and ...

  • Sickle Cell Anemia Detection 

    Anemia is a common name given to falls in oxygen transport capacity due to some of the functional disadvantages of red blood cells. Pathology Laboratorians put the tissue on the microscope glass and try to diagnose Anemia disease. Processes have been taken for a long time and it has been caused to distract. Therefore it has been caused to misdiagnose the Laboratorian. This work shortens the diagnostic period of the disease and to minimizes error probability of this diagnosis by extracting healthy ...

  • Signature verification using conic section function neural network 

    Authors:Şenol, Canan; Yıldırım, Tülay
    Publisher and Date:(2005)
    This paper presents a new approach for off-line signature verification based on a hybrid neural network (Conic Section Function Neural Network-CSFNN). Artificial Neural Networks (ANNs) have recently become a very important method for classification and verification problems. In this work CSFNN was proposed for the signature verification and compared with two well known neural network architectures (Multilayer Perceptron-MLP and Radial Basis Function-RBF Networks). The proposed system was trained ...

  • Signature verification using conic section function neural network 

    Authors:Şenol, Canan; Yıldırım, Tülay
    Publisher and Date:(Springer-Verlag Berlin, 2005)
    This paper presents a new approach for off-line signature verification based on a hybrid neural network (Conic Section Function Neural Network-CSFNN). Artificial Neural Networks (ANNs) have recently become a very important method for classification and verification problems. In this work CSFNN was proposed for the signature verification and compared with two well known neural network architectures (Multilayer Perceptron-MLP and Radial Basis Function-RBF Networks). The proposed system was trained ...