Browsing Elektrik-Elektronik Mühendisliği / Electrical - Electronics Engineering by Title
Now showing items 157-176 of 330
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Linear Combination of Pulses for Coexistence in the IEEE 802.15.4a Standard
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Publisher and Date:(IEEE, 2009)The low data rate accurate location ranging Wireless Personal Area Network zWPAN standard IEEE which is based on ultra wideband zUWBg impulse radios suggests using linear combination of pulses to reduce interference to coexisting primary systems. In this paper we consider possible implementations of linear combination of pulses as suggested in the standard and study the generated notches in the resulting code spectrum. Using the zy transform approach we show that the number of these notches is ...
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Linear expansions for frequency selective channels in OFDM
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Publisher and Date:(Elsevier GMBH Urban & Fischer Verlag, 2006)Modeling the frequency selective fading channels as random processes we employ a linear expansion based on the Karhumen-Loeve (KL) series representation involving a complete set of orthogonal deterministic vectors with a corresponding uncorrelated random coefficients. Focusing on OFDM transmissions through frequency selective fading this paper pursues a computationally efficient pilot-aided linear minimum mean square error (MMSE) uncorrelated KL series expansion coefficients estimation algorithm. ...
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Liquid-liquid equilibria of water+propionic acid+solvent ternaries at 298.2 K
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Publisher and Date:(2006)(Liquid + liquid) equilibrium (LLE) data for (water + propionic acid + solvent) were measured at T= 298.2 K and atmospheric pressure. The solvents were methyl isoamyl ketone (5-methyl-2-hexanone) and diisobutyl ketone. The tie-line data were predicted by the UNIFAC method. A comparison of the extracting capabilities of the solvents was made with respect to distribution coefficients separation factors and solvent free selectivity bases.
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Low-complexity joint data detection and channel equalisation for highly mobile orthogonal frequency division multiplexing systems
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Publisher and Date:(2010)This study is concerned with the challenging and timely problem of channel equalisation and data detection for orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency-selective and very rapidly time-varying channels. The algorithm is based on the space alternating generalised expectation-maximisation (SAGE) technique which is particularly well suited to multicarrier signal formats and can be easily extended to multi-input multi-output-OFDM systems. In fast fading ...
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Low-Complexity MAP-Based Successive Data Detection for Coded OFDM Systems Over Highly Mobile Wireless Channels
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Publisher and Date:(IEEE-INST Electrical Electronics Engineers Inc, 2011)This paper is concerned with the challenging and timely problem of data detection for coded orthogonal frequency-division multiplexing (OFDM) systems in the presence of frequency-selective and very rapidly time varying channels. New low-complexity maximum a posteriori probability (MAP) data detection algorithms are proposed based on sequential detection with optimal ordering (SDOO) and sequential detection with successive cancellation (SDSC). The received signal vector is optimally decomposed into ...
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Lower lower-critical spin-glass dimension from quenched mixed-spatial-dimensional spin glasses
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Publisher and Date:(Amer Physical Soc., 2018)By quenched-randomly mixing local units of different spatial dimensionalities we have studied Ising spin-glass systems on hierarchical lattices continuously in dimensionalities 1 <= d <= 3. The global phase diagram in temperature antiferromagnetic bond concentration and spatial dimensionality is calculated. We find that as dimension is lowered the spin-glass phase disappears to zero temperature at the lower-critical dimension d(c) = 2.431. Our system being a physically realizable system this sets ...
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MAP channel-estimation-based PIC receiver for downlink MC-CDMA systems
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Publisher and Date:(Hindawi Publishing Corporation, 2008)We propose a joint MAP channel estimation and data detection technique based on the expectation maximization (EM) method with paralel interference cancelation (PIC) for downlink multicarrier (MC) code division multiple access (CDMA) systems in the presence of frequency selective channels. The quality of multiple access interference (MAI) which can be improved by using channel estimation and data estimation of all active users affects considerably the performance of PIC detector. Therefore data and ...
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Mathematical Characterization of Thermo-reversible Phase Transitions of Agarose Gels
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Publisher and Date:(Taylor & Francis Inc, 2018)The thermal phase transition temperatures of high (HMP) and low melting point (LMP) agarose gels were investigated by using UV-vis spectroscopy techniques. Transmitted light intensities from the gel samples with different agarose concentrations were monitored during the heating (gel-sol) and cooling (sol-gel) processes. It was observed that the transition temperatures T-m defined as the location of the maximum of the first derivative of the sigmoidal transition paths obtained from the UV-vis ...
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Mathematical models for phase transitions in biogels
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Publisher and Date:(World Scientific Publ Co Pte Ltd, 2019)It has been shown that reversible and irreversible phase transitions of biogels can be represented by epidemic models. The irreversible chemical sol-gel transitions are modeled by the Susceptible-Exposed-Infected-Removed (SEIR) or Susceptible-Infected-Removed (SIR) epidemic systems whereas reversible physical gels are modeled by a modification of the Susceptible-Infected-Susceptible (SIS) system. Measured sol-gel and gel-sol transition data have been fitted to the solutions of the epidemic models, ...
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Maximally random discrete-spin systems with symmetric and asymmetric interactions and maximally degenerate ordering
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Publisher and Date:(Amer Physical Soc., 2018)Discrete-spin systems with maximally random nearest-neighbor interactions that can be symmetric or asymmetric ferromagnetic or antiferromagnetic including off-diagonal disorder are studied for the number of states q = 34 in d dimensions. We use renormalization-group theory that is exact for hierarchical lattices and approximate (Migdal-Kadanoff) for hypercubic lattices. For all d > 1 and all nonmfimte temperatures the system eventually renormalizes to a random single state thus signaling q x q ...
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Metastable reverse-phase droplets within ordered phases: Renormalization-group calculation of field and temperature dependence of limiting size
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Publisher and Date:(AMER PHYSICAL SOC, 2020)Metastable reverse-phase droplets are calculated by renormalization-group theory by evaluating the magnetization of a droplet under magnetic field, matching the boundary condition with the reverse phase and noting whether the reverse-phase magnetization sustains. The maximal metastable droplet size and the discontinuity across the droplet boundary are thus calculated as a function of temperature and magnetic field for the Ising model in three dimensions. The method also yields hysteresis loops for ...
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Minimum Length Scheduling for Discrete Rate Based Full Duplex Wireless Powered Communication Networks
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Publisher and Date:(Springer, 2019)In this study, we consider a wireless powered communication network where multiple users with radio frequency energy harvesting capabilities communicate to a hybrid energy and information access point in full duplex mode. We characterize an optimization framework for minimum length scheduling to determine the optimal rate adaptation and transmission scheduling subject to energy causality and traffic demand constraints of the users considering discrete-rate transmission model. We first formulate ...
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Minimum Length Scheduling for Full Duplex Time-Critical Wireless Powered Communication Networks
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Publisher and Date:(IEEE, 2020)Radio frequency (RF) energy harvesting is key in attaining perpetual lifetime for time-critical wireless powered communication networks (WPCNs) due to full control on energy transfer, far field region, small and low-cost circuitry. In this paper, we propose a novel minimum length scheduling problem to determine the optimal power control, time allocation and schedule subject to data, energy causality and maximum transmit power constraints in a full-duplex WPCN. We first formulate the problem as a ...
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Mixed Element Networks With Series Capacitors Separated By Unit Elements
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Publisher and Date:(World Scientific, 2020)In this work, high-pass mixed-element networks with series capacitors separated by unit elements are analyzed. First, the description of the networks via two frequency variables is given. Then, explicit coefficient relations for the descriptive polynomials are derived in terms of the single-variable boundary polynomial coefficients. Finally, the derived relations are used to design a high-pass mixed-element matching network. The series capacitors can be converted to short-ended stubs by means of ...
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Mobile Application Development for the Estimation of Recurrence in Post-Operative Kidney Cancer Cases
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Publisher and Date:(IEEE, 2018)In this paper a post-operative recurrence estimation tool called Sorbellini's nomogram for the kidney cancer patients showing no metastates is introduced and a novel application for mobile devices based on this model is developed for the physician's follow up procedures. The TNM stage tumor size nuclear (Fuhrman) grade the existance of necrosis and vascular invasion are employed as the input parameters for this software to predict the recurrence probability in mentioned patients. Finaly the ...
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Modeling and Equalization of Indoor Visible Light Channnels
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Publisher and Date:(IEEE, 2016)In this paper a computationally efficient method is proposed for modeling the indoor visible light communications (VLC) channels using a non-sequential ray tracing technique. We created three dimensional realistic simulation environment to depict indoor scenarios specifying the geometry of the indoor environment the objects inside the reflection characteristics of the surface materials as well as the characteristics of the transmitter and receiver. We then compute the received optical power and ...
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Modeling based real frequency technique
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Publisher and Date:(Elsevier GMBH Urban & Fischer Verlag, 2008)Usually commercially available software tools are used to design matching networks for wireless communication systems. But a properly selected matching network topology with good initial element values must be supplied to these tools. Therefore in this paper a modeling-based real frequency technique (M-RFT) is presented to generate matching networks with initial element values. In the proposed method output impedance data of the matching network are obtained in terms of ABCD-parameters of the load ...
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Modeling of Visible Light Channels and Performance Analysis of ACO-OFDM
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Publisher and Date:(IEEE, 2015)Spectrum scarcity of traditional radio communication has led communication engineers to find new alternatives. Indoor visible light communication is one alternative to solve this problem since its spectrum is not regulated and it has much wider bandwidth then traditional communication systems. This increased the research done in the field of visible light communications. However a proper indoor channel model is lacking and all previous studies assumes that only additive white Gaussian noise (AWGN) ...
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Modified Q-Based Real Frequency Design of Narrowband Impedance Equalizer with Complex Terminations
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Publisher and Date:(World Scientıfic Publ Co Pte Ltd, 2019)In this paper, real frequency design equations of narrowband impedance matching network with complex terminations are derived; which are used to design L, Pi and T type of networks. In the approach, there is no need to have termination models with component values, it is enough to have measurement values of termination impedances. A few examples are solved to exhibit the have measurement values of termination impedances. A few examples are solved to exhibit the merits and application of the derived ...
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Monte Carlo Solutions for Blind Phase Noise Estimation
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Publisher and Date:(Springer International Publishing Ag, 2009)This paper investigates the use of Monte Carlo sampling methods for phase noise estimation on additive white Gaussian noise (AWGN) channels. The main contributions of the paper are (i) the development of a Monte Carlo framework for phase noise estimation with special attention to sequential importance sampling and Rao-Blackwellization (ii) the interpretation of existing Monte Carlo solutions within this generic framework and (iii) the derivation of a novel phase noise estimator. Contrary to the ...