System Level Evaluation of Innovative Coded MIMO-OFDM Systems for Broadcasting Digital TV

Single-frequency networks (SFNs) for broadcasting digital TV is a topic of theoretical and practical interest for future broadcasting systems. Although progress has been made in the characterization of its description, there are still considerable gaps in its deployment with MIMO technique. The contribution of this paper is multifold. First, we investigate the possibility of applying a space-time (ST) encoder between the antennas of two sites in SFN. Then, we introduce a 3D space-time-space block code for future terrestrial digital TV in SFN architecture. The proposed 3D code is based on a double-layer structure designed for intercell and intracell space time-coded transmissions. Eventually, we propose to adapt a technique called effective exponential signal-to-noise ratio (SNR) mapping (EESM) to predict the bit error rate (BER) at the output of the channel decoder in the MIMO systems. The EESM technique as well as the simulations results will be used to doubly check the efficiency of our 3D code. This efficiency is obtained for equal and unequal received powers whatever is the location of the receiver by adequately combining ST codes. The 3D code is then a very promising candidate for SFN architecture with MIMO transmission

Susceptibility Amplitude Ratios Near a Lifshitz Point

The susceptibility amplitude ratio in the neighborhood of a uniaxial Lifshitz point is calculated at one-loop level using field-theoretic and $\epsilon_{L}$-expansion methods. We use the Schwinger parametrization of the propagator in order to split the quadratic and quartic part of the momenta, as well as a new special symmetry point suitable for renormalization purposes. For a cubic lattice (d = 3), we find the result $\frac{C_{+}}{C_{-}} = 3.85$.Comment: 7 pages, late

Single cell mechanics: stress stiffening and kinematic hardening

Cell mechanical properties are fundamental to the organism but remain poorly understood. We report a comprehensive phenomenological framework for the nonlinear rheology of single fibroblast cells: a superposition of elastic stiffening and viscoplastic kinematic hardening. Our results show, that in spite of cell complexity its mechanical properties can be cast into simple, well-defined rules, which provide mechanical cell strength and robustness via control of crosslink slippage.Comment: 4 pages, 6 figure

Experimental and numerical investigation of hybrid laser arc welding process and the influence of welding sequence on the manufacture of stiffened flat panels

La soldadura por arco láser híbrido (HLAW) ha atraído cada vez más atención tanto de la industria como de los laboratorios académicos por su alta eficiencia y calidad de soldadura. El objetivo del presente artículo es desarrollar un método de elementos finitos no lineal para predecir la deflexión inducida por la soldadura y la tensión residual de un panel rígido a escala semiindustrial, utilizando un nuevo modelo de fuente de calor. La nueva fuente de calor híbrida consiste en un modelo matemático de doble elipsoide de Goldak que representa la fuente del arco, combinado con un modelo matemático gaussiano de cono truncado para simular la fuente láser. Para ello, se ha desarrollado un modelo de elementos finitos termoelástico-plástico acoplado tridimensional con ABAQUS utilizando una subrutina numérica adicional de DFLUX escrita en el lenguaje de programación Fortran para simular las distribuciones volumétricas de flujo de calor del proceso HLAW. El método de elementos finitos (FEM) se verifica mediante comparación con mediciones experimentales de muestras de acero naval EH36 de pequeña escala con uniones en T, en configuración a tope en posición de soldadura 2F, soldadas en posición horizontal con penetración total mediante un proceso híbrido de soldadura por arco láser (HLAW). Se observa una buena concordancia entre los resultados numéricos y las mediciones experimentales, lo que confirma que el modelo desarrollado en el presente artículo se puede utilizar eficazmente para predecir el comportamiento de deformación de las estructuras de rigidizadores durante la construcción naval. También se ha estudiado el efecto del cambio de secuencia de soldadura en el panel rígido a escala semiindustrial. Se han investigado cuatro secuencias de soldadura diferentes (SEQ 1,2,3 y 4), para elegir la mejor secuencia de soldadura en cuanto a la magnitud y distribución de las imperfecciones de soldadura (deflexión y tensión residual). Cambiar la secuencia de soldadura tiene un efecto significativo en la distribución y magnitud de la deflexión vertical. Se concluye que la secuencia de soldadura juega un papel importante en la deformación de las estructuras. Un cambio de dirección en la sección media, en combinación con la alternancia de las trayectorias de soldadura entre dos refuerzos consecutivos, conduce a una disminución significativa de la distorsión. El modelo FEM desarrollado ha proporcionado resultados precisos, lo que demuestra que es aplicable para estimar la deformación y la tensión residual inducida por el proceso HLAW en estructuras de construcción naval más grandes. También se puede emplear para optimizar la secuencia de soldadura. La presente contribución forma parte de un proyecto de colaboración entre la Universidad de Cádiz y la Universidad de Alejandría, Egipto, coordinado por el solicitante (J.M. Sánchez Amaya), cuyo principal objetivo es profundizar en el conocimiento y aplicación de las simulaciones FEM a procesos de soldadura. Este proyecto ha sido posible gracias a la financiación, por parte de la Comisión de la Unión Europea, de la beca de programa Erasmus + KA107, que ha permitido cubrir los gastos del viaje de Ahmed Hammad a la UCA. El solicitante (J.M. Sánchez Amaya) ha realizado las siguientes actividades del manuscrito: responsable y coordinador del conjunto de actividades de la colaboración; comparativa y análisis de resultados de las soldaduras HLAW; análisis y discusión de resultados del artículo; y revisión inicial y final del manuscrito

A comparative study for estimating the parameters of the second order moving average process

EnMoving Average process is a representation of a time series written as a finite linear combination of uncorrelated random variables. Our main interest is to compare a classical estimation method; namely Exact Maximum Likelihood Estimation (EMLE) with the Generalized Maximum Entropy (GME) approach for estimating the parameters of the second order moving average processes. In this paper, in applying EMLE we have to find the exact likelihood function through deriving the probability density function of the series. Differentiating the function with respect to the parameters, we can obtain the exact maximum likelihood estimates. On the other hand, the idea of GME is to write the unknown parameters and error terms as the expected value of some proper probability distributions defined over some supports. We carry a simulation study to compare between the presented estimation techniques

Closed-form sums for some perturbation series involving associated Laguerre polynomials

Infinite series sum_{n=1}^infty {(alpha/2)_n / (n n!)}_1F_1(-n, gamma, x^2), where_1F_1(-n, gamma, x^2)={n!_(gamma)_n}L_n^(gamma-1)(x^2), appear in the first-order perturbation correction for the wavefunction of the generalized spiked harmonic oscillator Hamiltonian H = -d^2/dx^2 + B x^2 + A/x^2 + lambda/x^alpha 0 0, A >= 0. It is proved that the series is convergent for all x > 0 and 2 gamma > alpha, where gamma = 1 + (1/2)sqrt(1+4A). Closed-form sums are presented for these series for the cases alpha = 2, 4, and 6. A general formula for finding the sum for alpha/2 = 2 + m, m = 0,1,2, ..., in terms of associated Laguerre polynomials, is also provided.Comment: 16 page

Tracking transplanted bone marrow stem cells and their effects in the rat MCAO stroke model.

In this study, rat bone marrow stromal stem cells (BMSCs) were tracked after IV administration to rats with experimental stroke caused by middle cerebral artery occlusion (MCAO). In addition, the effects of BMSC treatment on blood cell composition, brain glia and sensorimotor behavior was studied and compared to that which occurred spontaneously during the normal recovery process after stroke. We found that the vast majority of radiolabeled or fluorescently labeled BMSCs traveled to and remained in peripheral organs (lungs, spleen, liver) 3 days after IV injection in the MCAO rat. Once in the circulation, BMSCs also produced rapid alterations in host blood cell composition, increasing both neutrophil and total white blood cell count by 6 hours post-injection. In contrast, few injected BMSCs traveled to the brain and almost none endured there long term. Nonetheless, BMSC treatment produced dramatic changes in the number and activation of brain astroglia and microglia, particularly in the region of the infarct. These cellular changes were correlated with a marked improvement in performance on tests of sensory and motor function as compared to the partial recovery of function seen in PBS-injected control rats. We conclude that the notable recovery in function observed after systemic administration of BMSCs to MCAO rats is likely due to the cellular changes in blood and/or brain cell number, activation state and their cytokine/growth factor products

Effective Mass Dirac-Morse Problem with any kappa-value

The Dirac-Morse problem are investigated within the framework of an approximation to the term proportional to $1/r^2$ in the view of the position-dependent mass formalism. The energy eigenvalues and corresponding wave functions are obtained by using the parametric generalization of the Nikiforov-Uvarov method for any $\kappa$-value. It is also studied the approximate energy eigenvalues, and corresponding wave functions in the case of the constant-mass for pseudospin, and spin cases, respectively.Comment: 12 page