Abstract
In presented work, the tunable characteristics of magnetic fluid refractive index under the influence of magnetic field with single mode fiber (SMF) with tapered structure are investigated. The sensing fiber probe consists of special down taper joints formed by fusion splicer. Experimental result indicates that the proposed device has excellent magnetic fluid refractive index tunability. The sensitive performances of the sensors are controlled by designing the parameters of the tapered structure and the concentration of Magnetic fluid. Experimental result used to carry out to achieve the magnetic field (intensity and direction) dependent refractive index of the magnetic fluid. © OSA 2016.

Abstract

Abstract
The concern about injuries in sport are evident due to the implications it carries. To have the knowledge of the mechanisms of injuries is important either to prevent and recovery. This context generates the appropriate scenario to develop an electronic solution to measure dynamically the Center of Pressure (CoP) and surfboard's movement and support the understanding of the mechanisms responsible for the occurrence of injuries. Two matrices composed by 24 force sensors and Inertial Measurement Unit (IMU) controlled by ATEMEGA1280 microcontroller were developed. This system was tested using a dynamic protocol using one unstable structure at the bottom of the surfboard. The results have shown that the CoP displacement was largest during the tests that presented great rotation changes. Furthermore, the power oscillations were greater during transition moments. The proposed system is able to measure biomechanical variables dynamically, i.e., force, and surfboard's angle pitch and roll. This report reviews the surf injuries in literature and describes the electronic device used beyond to present the results of the tests performed.

Abstract
In this paper, we propose a new channel estimation (CE) structure that aims to minimize the mean square error (MMSE) of orthogonal frequency-division multiplexing signals that are corrupted by fading, nonlinear, and additive white Gaussian noise channels. We demonstrate that it exhibits a simple structure consisting of a set of correlators matched to every frequency component in the nonlinearly distorted signal, followed by a linear transformation. An extension suitable for frequency shifted signals is also discussed. As case study, the potential of such CE in uplink radio-over-fiber (RoF) systems conveying WiFi signals is analyzed. Through simulations, we demonstrate the usage of the one-tap and iterative maximum likelihood (ML)-algorithm-based equalizers, when used jointly with the proposed MMSE, zero forcing, or perfect CEs. Results show that the performance of the MMSE CE approximates the one of the perfect CE. In addition, when used in conjunction with the ML algorithm, it enables relaxation of linear requirements of components in RoF by passing the need for transmitter predistortion techniques that would otherwise significantly increase wireless devices complexity.

Abstract
Sparse coding techniques have seen an increasing range of applications in recent years, especially in the area of image processing. In particular, sparse coding using l1-regularization has been efficiently solved with the Augmented Lagrangian (AL) applied to its dual formulation (DALM). This paper proposes the decomposition of the dictionary matrix in its Singular Value/Vector form in order to simplify and speed-up the implementation of the DALM algorithm. Furthermore, we propose an update rule for the penalty parameter used in AL methods that improves the convergence rate. The SVD of the dictionary matrix is done as a pre-processing step prior to the sparse coding, and thus the method is better suited for applications where the same dictionary is reused for several sparse recovery steps, such as block image processing. © 2014 IEEE.

Abstract