Abstract
Due to strong improvements and developments achieved in the last decade, it is clear that applied research using remote sensing technology such as unmanned aerial vehicles (UAVs) can provide a flexible, efficient, non-destructive, and non-invasive means of acquiring geoscientific data, especially aerial imagery. Simultaneously, there has been an exponential increase in the development of sensors and instruments that can be installed in UAV platforms. By combining the aforementioned factors, unmanned aerial system (UAS) setups composed of UAVs, sensors, and ground control stations, have been increasingly used for remote sensing applications, with growing potential and abilities. This paper's overall goal is to identify advantages and challenges related to the use of UAVs for aerial imagery acquisition in forestry and coastal environments for preservation/prevention contexts. Moreover, the importance of monitoring these environments over time will be demonstrated. To achieve these goals, two case studies using UASs were conducted. The first focuses on phytosanitary problem detection and monitoring of chestnut tree health (Padrela region, Valpacos, Portugal). The acquired high-resolution imagery allowed for the identification of tree canopy cover decline by means of multi-temporal analysis. The second case study enabled the rigorous and non-evasive registry process of topographic changes that occurred in the sandspit of Cabedelo (Douro estuary, Porto, Portugal) in different time periods. The obtained results allow us to conclude that the UAS constitutes a low-cost, rigorous, and fairly autonomous form of remote sensing technology, capable of covering large geographical areas and acquiring high precision data to aid decision support systems in forestry preservation and coastal monitoring applications. Its swift evolution makes it a potential big player in remote sensing technologies today and in the near future.

Abstract
The use of Augmented Reality (AR) techniques to visualize virtual archaeological sites is neither a new or recent issue. In those approaches the virtual models are only visualized using the existent in situ illumination, which does not allow a visitor to have a similar visual experience to that which he would have at the time the structures were built. In Augmented Virtuality (AV) approaches the virtual world prevails, which is augmented with information from the real world, which allows a better control over the parameters of the Mixed Reality (MR) environment created. In some cases, there is the need to use both approaches (AR or AV), depending on some context conditions. This paper proposes an architecture and an information system for an adaptive MR system which main goal is to visualize in situ virtual reconstructions of archaeological sites that are seamlessly merged with the real scene. In this context, a new adaptive methodology will be defined to manage the level of mixing between the real and the virtual scene, identifying in each instant the most proper approach to use (AR or AV), as well as defining the way how transitions between approaches are made. (C) 2014 The Authors. Published by Elsevier Ltd.

Abstract
Interaction plays a fundamental role as it sets bridges between humans and computers. However, people with disability are prevented to use computers by the ordinary means, due to physical or intellectual impairments. Thus, the human-computer interaction (HCI) research area has been developing solutions to improve the technological accessibility of impaired people, by enhancing computers and similar devices with the necessary means to attend to the different disabilities, thereby contributing to reduce digital exclusion. Within the aforementioned scope, this paper presents an interaction solution for upper limb amputees, supported on a myographic gesture-control device named Myo. This device is an emergent wearable technology, which consists in a muscle-sensitive bracelet. It transmits myographic and inertial data, susceptible of being converted into actions for interaction purposes (e.g. clicking or moving a mouse cursor). Although being a gesture control armband, Myo can also be used in the legs, as was ascertained through some preliminary tests with users. Both data types (myographic and inertial) remain to be transmitted and are available to be converted into gestures. A general architecture, a use case diagram and the two main functional modules specification are presented. These will guide the future implementation of the proposed Myo-based HCI solution, which is intended to be a solid contribution for the interaction between upper limb amputees and computers. (C) 2016 The Authors. Published by Elsevier B.V.

Abstract
This paper discusses the teaching of Fourier Series concepts in undergraduate Electrical Engineering education with the help of an Android application, especially developed to that end. In order to better understand the links and implications, some of the basic Fourier series theory is briefly reviewed. The Android application has an easy-to-use, friendly interface, conceived to help undergraduate students test and assess the Fourier series expansions on a typical set of signals. The application also allows the students to control the total approximation error and the number of terms/harmonics used in the expansions. It has been found a very useful learning resource in the Fourier series context.

Abstract
Here we discuss the teaching of Fourier series concepts in connection with undergraduate Electrical Engineering education. We briefly review some of the basic Fourier series theory, and present an Android application that has been found useful in this context. As expected, the application has an easy-to-use, friendly interface, and can be viewed as a tool to help undergraduate students test and assess the Fourier series expansions on a typical set of signals, whose analytical Fourier series coefficients were found during the theoretical lectures. Additionally, students can also control the total approximation error and the number of terms/harmonics used in the expansion. It seems that our students prefer this Android application to the traditional applet fashioned web-based applications.

Abstract
The aim of this study is twofold: first, to present a survey of the actual and most advanced methods related to the use of unmanned aerial systems (UASs) that emerged in the past few years due to the technological advancements that allowed the miniaturization of components, leading to the availability of small-sized unmanned aerial vehicles (UAVs) equipped with Global Navigation Satellite Systems (GNSS) and high quality and cost-effective sensors; second, to advice the target audience - mostly farmers and foresters - how to choose the appropriate UAV and imaging sensor, as well as suitable approaches to get the expected and needed results of using technological tools to extract valuable information about agroforestry systems and its dynamics, according to their parcels' size and crop's types. Following this goal, this work goes beyond a survey regarding UAS and their applications, already made by several authors. It also provides recommendations on how to choose both the best sensor and UAV, in according with the required application. Moreover, it presents what can be done with the acquired sensors' data through theuse of methods, procedures, algorithms and arithmetic operations. Finally, some recent applications in the agroforestry research area are presented, regarding the main goal of each analysed studies, the used UAV, sensors, and the data processing stage to reach conclusions.