Two Proposed Blind Equalizers Using Different Constellation Matched Error Functions for QAM Signals

Although Constant Modulus Algorithm (CMA) is effective to equalize non-minimum phase channels blindly, it suffers from residual intersymbol interference (ISI) and large Mean Square Error (MSE) when applied to higher order constellations (QAM). Methods based on cost function matched to the signal constellation namely alphabet matched algorithm (AMA) were previously reported and proves its superiority on CMA concerning the MSE. Thus dual mode algorithms between CMA and AMA were introduced. A hybrid technique combining CMA and AMA using a cosine square function as a constellation matched error (CME) was lately reported. In this paper two different CME functions are introduced. The MSE of the proposed algorithms are calculated using Matlab simulation under multipath slow fading channels for different signal to noise ratios (SNR) and different levels of QAM constellations. A comparison is established among them. Depicted results show the effectiveness of the two proposed CME functions. Hebat-Allah M. Mourad received her B.Sc., M.Sc. and Ph.D. degrees in electrical communication engineering from Cairo University, Egypt, in 1983, 1987 and 1994 respectively. Since 1983, she has been with the Department of Electronics and Communications, Faculty of Engineering, Cairo University, and is currently associate professor there. Her research interests include optical fiber communications, mobile and satellite communications.     

Link Adaptation Based on Explicit Channel Estimation for Throughput Maximization Over Rayleigh Fading Channels

Link Adaptation (LA) has been proposed in the literature as a means of increasing the throughput obtained by each user in wireless communication systems. Due to its significant simplicity, LA has even been adopted as the standard adaptive coding technique for the next generation mobile communication system known as EDGE. In this paper, we present a novel link adaptation technique, valid for use in the case of Rayleigh fading wireless channels. The new technique is based on the blind channel estimation algorithm usually used for combating inter-symbol interference (ISI). The algorithm is presented and its efficiency in providing the maximum available throughput is illustrated by means of computer simulations.     

Mixed Wavelet Leaders Multifractal Formalism in a Product of Critical Besov Spaces

In this paper, we will prove (resp. study) the Baire generic validity of the upper-Hölder (resp. iso-Hölder) mixed wavelet leaders multifractal formalism on a product of two critical Besov spaces \(B_{t_{1}}^{\frac{m}{t_{1}},q_{1}}(\mathbb {R}^m) \times B_{t_{2}}^{\frac{m}{t_{2}},q_{2}}(\mathbb {R}^m)\), for \(t_1,t_2>0\), \(q_1 \le 1\) and \(q_2 \le 1\). Contrary to product spaces \(B_{t_{1}}^{s_{1},\infty }(\mathbb {R}^m) \times B_{t_{2}}^{s_{2},\infty }(\mathbb {R}^m) \) with \(s_{1} > \frac{m}{t_{1}}\) and \(s_{2} >\frac{m}{t_{2}}\) (Ben Slimane in Mediterr J Math, 13(4):1513–1533, 2016) and \((B_{t_{1}}^{s_{1},\infty }(\mathbb {R}^m) \cap C^{\gamma _{1}}(\mathbb {R}^m)) \times (B_{t_{2}}^{s_{2},\infty }(\mathbb {R}^m) \cap C^{\gamma _{2}}(\mathbb {R}^m)\) with \(0<\gamma _{1}<s_{1}<\frac{m}{t_{1}}\) and \(0<\gamma _{2}<s_{2}<\frac{m}{t_{2}}\) (Ben Abid et al. in Mediterr J Math, 13(6):5093–5118, 2016), all pairs of functions in the obtained generic set are not uniform Hölder. Nevertheless, the characterization of the upper bound of the Hölder exponent by decay conditions of local wavelet leaders suffices for our study.     

On the Calderón problem in periodic cylindrical domain with partial Dirichlet and Neumann data

We consider the Calderón problem in an infinite cylindrical domain, whose cross section is a bounded domain of the plane. We prove log–log stability in the determination of the isotropic periodic conductivity coefficient from partial Dirichlet data and partial Neumann boundary observations of the solution. Copyright © 2017 John Wiley & Sons, Ltd.     

The Foldy‐Lax approximation of the scattered waves by many small bodies for the Lamé system

We are concerned with the linearized, isotropic and homogeneous elastic scattering problem by many small rigid obstacles of arbitrary, Lipschitz regular, shapes in 3D case. We prove that there exist two constants a₀ and c₀, depending only on the Lipschitz character of the obstacles, such that under the conditions and on the number M of the obstacles, their maximum diameter a and the minimum distance between them d, the corresponding Foldy‐Lax approximation of the farfields is valid. In addition, we provide the error of this approximation explicitly in terms of the three parameters and d. These approximations can be used, in particular, in the identification problems (i.e. inverse problems) and in the design problems (i.e. effective medium theory).     

Comparison of theoretical and measured P1dB of a photonic microwave link: influence of some physical parameters of the DFB laser

This paper studies a microwave photonic link built as an IM/DD or intensity modulation–direct detection semiconductor laser system. The radiofrequency gain and 1 dB compression point of the link are both simulated with a modelling approach and compared to measurements. The electrical model of the electro-optic transducer, a distributed feedback laser, is first presented. Taking into account the nonlinearities and noise sources, it is developed on the commercial electrical software Advanced Design System. Owing to this accurate model, the impact of the relaxation oscillation frequency is presented on the system nonlinearity characteristic as for example the input 1 dB compression point. The comparison of simulated results to measured ones confirms the accuracy of this model.     

A low cost implementation of the Phillips model in solid–liquid flow modeling

The interpolation requirements for the loosely coupled finite element solution of the Navier–Stokes equations and Phillips shear‐induced particle diffusion model are discussed. It is shown that a second‐order approximation of the fluid velocity field is required to adequately capture the spatial derivatives of the rate‐of‐strain tensor. To circumvent this limitation, a shear‐rate smoothing procedure is introduced, thereby allowing the use of lower‐order approximations for the fluid phase. Numerical experiments comparing the convergence and CPU cost of the different tetrahedral interpolation bases are presented. Copyright © 2009 John Wiley & Sons, Ltd.     

Electrical characterization and modeling of Au/MEH-PPV/porous n+-GaAs/n+-GaAs heterojunction in direct and alternating current mode

Assembled heterojunction was fabricated by spin-coating poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene-vinylene)] (MEH-PPV) thin layers on straight and porous n⁺-GaAs substrates. The current–voltage and capacitance–voltage studies have shown an abrupt junction behavior with current conduction governed by SCLC and thermionic modes. Andersons' rules were used to determine depletion width and balance bands discontinuities for both heterojunctions. Capacitance and conductance vs. frequency techniques were used to evaluate the density of interface states. Density values obtained from both techniques were in a good agreement.     

The effect of thiourea as a complexing agent on the separation of metallic ions through cation exchange membranes by Donnan dialysis

Donnan dialysis has been investigated in this work in the order to exhibit the influence of the composition of solution on the performance of commercial cation exchange membrane toward metallic ions. Transference fluxes have been determined either as experimental values or calculated according to theoretical models. A good agreement between theoretical and experimental flows has been obtained principally in the case of CMV membrane which presents a lower thickness. It has been demonstrated that addition of thiourea causes an increase of separation properties of membrane. The separation is mainly due to the complex formation between Ag⁺ and Cu⁺ ions and thiourea. Monovalent copper ion is obtained after reduction of Cu²⁺ and oxidation of thiourea and formation of bisulfide of formamidine which constitute a barrier to monovalent complex transference.     

Efficient UV-light photocatalytic activity of TiO2@Phosphogypsum composite synthesized by sol–gel method

Optical and Quantum Electronics - All optical multiband radio transceiver is designed using Polarization Modulators. Polarization Modulators have been gaining popularity in recent times as the...