Abstract

Abstract

Abstract
Hand and finger tracking has a major importance in healthcare, for rehabilitation of hand function required due to a neurological disorder, and in virtual environment applications, like characters animation for on-line games or movies. Current solutions consist mostly of motion tracking gloves with embedded resistive bend sensors that most often suffer from signal drift, sensor saturation, sensor displacement and complex calibration procedures. More advanced solutions provide better tracking stability, but at the expense of a higher cost. The proposed solution aims to provide the required precision, stability and feasibility through the combination of eleven inertial measurements units (IMUs). Each unit captures the spatial orientation of the attached body. To fully capture the hand movement, each finger encompasses two units (at the proximal and distal phalanges), plus one unit at the back of the hand. The proposed glove was validated in two distinct steps: a) evaluation of the sensors' accuracy and stability over time; b) evaluation of the bending trajectories during usual finger flexion tasks based on the intra-class correlation coefficient (ICC). Results revealed that the glove was sensitive mainly to magnetic field distortions and sensors tuning. The inclusion of a hard and soft iron correction algorithm and accelerometer and gyro drift and temperature compensation methods provided increased stability and precision. Finger trajectories evaluation yielded high ICC values with an overall reliability within application's satisfying limits. The developed low cost system provides a straightforward calibration and usability, qualifying the device for hand and finger tracking in healthcare and animation industries.

Abstract
A multimodal interferometer based on a new microstructured fiber tip is proposed for detection of the evaporation process of acetone. The new geometry consists of a capillary tube in which an offset Ge-doped core is fused and spliced at the end of a single-mode fiber. The fiber tip sensor structure was immersed in liquid acetone and the evaporation process of acetone was monitored in real time. Due to the refractive index variation of the external medium with increasing temperature, a short detection time of similar to 1 s was achieved. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)

Abstract
There are several factors such as the chosen optical source, central wavelength, spectral bandwidth, spectrometer optical components and the detector specifications that affect the overall performance of a spectral domain optical coherence tomography (SD-OCT) imaging system. Among these factors a good design and implementation of the spectrometer is of paramount importance as it directly affects the system resolution, sensitivity fall-off, maximum imaging depth, SNR and in general the system performance. This study demonstrates the design steps and some considerations during the design of a spectrometer. The imaging performance of this design is assessed. The obtained experimental results prove an improvement of the overall performance of the common path SD-OCT imaging system and agree with the expected outcome from the design stage.

Abstract
This paper aims to examine the process of reservoir sedimentation, namely to try to estimate the sediment volume deposited in the main Portuguese reservoirs. The changes in fluvial sediment transport induced by the construction of dams on the major Portuguese rivers are described. Based on the values of dead volumes, the current situation of 166 Portuguese reservoirs is analysed to obtain an order of magnitude of available sediments and pre-select reservoirs that could potentially be integrated into a project for the artificial sand nourishment of beaches. This work was carried out as a starting point in order to implement a national plan for the use of reservoir sediments as an "added value" to the economy, which is as yet generally unexploited. © 2014 Taylor & Francis Group, London.