RCAAP Repository

This article is build on the experience of using Google Earth Engine as a development framework for a previous work by the same authors.Being primarily a distributed parallel computing platform, it is designed around a functional language pattern, even though supported on an object model, and a map / reduce distributed workload paradigm.Leveraging the sheer computing power delivered by the Google infrastructure and a multi petabyte remote sensing data repository, GoogleEarth Engine is an efficient development framework that presents itself in two basic flavors: one online integrated development environment which uses the browser Javascript engine; two APIs that can be deployed to a Python or a NodeJS environment.This work emphasizes the comparison between the Javascript browserbased implementation and the Python environment packages.

Seamless access to updated information about mobility options is a key factor for sustainable economic development. In this context, the adoption of information systems, with innovative features, meet these needs by stimulating the interest and curiosity of end users. There are well known difficulties, even for regular travelers, to get the most suitable mobility options combining available transport modes. Also, the sustainable mobility has become the new imperative for transport policy. In this paper we present a collaborative platform that supports a Social Network, in which users can search and share sustainable mobility experiences. This platform includes a reputation and a recommender systems specially designed to deal with mobility options.

The Internet of Things (IoT) promotes interconnectivity between devices and these keep appearing in larger quantities throughout the years, with the evolution of communication technologies. However, scalability comes with a price, since for a higher quantity of devices comes the need for better transmission channels, with higher reach, availability and improved security capabilities. The infrastructure that comes with this ubiquitous network is very expensive so there is a need for finding low-cost solutions for the transmission of data, benefiting from the qualities of the optical fibers.Wireless technologies already provide a way to solve these issues, but the use of optical fibers would give to the IoT their own unique features, such as high bandwidth, long reach, signal integrity and high security. But IoT devices should not be power hungry nor have very limiting electrical-to-optical conversions, so a passive optical communications module based of fiber Bragg gratings for long reach and for the upload of information with low data rates should be implemented. This module would be integrated in the IoT ecosystem by connecting it to the existent dark fibers all over the world.A simulator of this module was implemented, capable of reproducing its characteristics for the transmission of information modulated in Frequency-Shift Keying and On-Off Keying modulation schemes. The study of the system performance for these schemes was made by estimating the Bit Error Rate using the Error Vector Magnitude metric, in relation to the received optical power.

In this paper, we address the problem of minimizing the total water consumption over the period of a year used to supply different fields with different types of crops.We start by recalling a previous study, where the authors developed an optimal control model for this problem by minimizing the water flowing into a reservoir and where the water from the precipitation can be collected. The numerical solution obtained using such model is analyzed.The main result in this paper is the theoretical validation of the numerical solution via a verifications that such solution satisfies the necessary conditions of optimality in the form of a Maximum Principle. This way, we are giving further evidence of the optimality of the numerical solution found.

Abstract: This paper presents an architecture for wireless sensor networks (WSN) operating in the 2.4GHz RF band for implementation in environments of small tunnels. The study begins with an objective description of the RF architecture and with the implementation of a RSSI analysis in real scenarios. The designed modules are using directional and omnidirectional antennas for each test scenario. In initial experiment is included a test on the 433Mhz band. The developed WSN architecture provides a higher degree of reliability at environments with denser structures (tunnels) and enables the use of directional and omnidirectional antennas for better signal behavior considering the structure of environment to propagation.

Graphene [1] is a material that has been extensively explored in recent years as a material with optical properties that enable its application as active material in sensing devices.In this work we will study plasmonic effects and optical properties of graphene and metal nanoparticles (AuNPs), comparing its results, whenever possible, with results obtained in previous studies. Analysis will be supported by simulation results obtained with Matlab (“Mie analysis”).

Current mobile devices (e.g., smartphones) are equipped with several sensors that allow different forms of userinteraction. They also offer several connectivity options and a growing computing power which supports itsuse in new Human Computer Interaction (HCI) scenarios. This paper presents the mobileWheel, a system thatexploits the capabilities of current mobile devices as a means of interaction with a real-time graphical drivingsimulation running on a desktop computer. The application on the mobile device performs data acquisitionfrom various sensors (focusing on the 3D accelerometer) and also provides different types of feedback tothe user. This system represents a ubiquitous, simple and affordable alternative approach to the traditionalcontrol of virtual vehicles in driving simulators and could also be applied in other similar architectures. Toevaluate and validate this approach several tests were conducted with volunteer users. The control mode wherethe virtual vehicle is fully controlled by the accelerometer had the highest acceptance and produced the bestresults.

In recent years, lighting solutions have gradually been replaced by more efficient features, taking advantage of Light Emitting Diodes (LEDs) that have progressively conquered the market with increasingly high optical powers, low energy consumption and variable color temperatures. Along with this evolution, Visible Light Communication (VLC) technology has also been developed to use this existing lighting infrastructure and the inherent characteristic of LEDs being easily switched to high frequency to build data transmission systems. The applications of this communication technology using electromagnetic signals in the visible range are currently in a development stage with promising applications in several domains.This paper intends to study an optical communication system based on VLC to establish communication between road infrastructures and. vehicles. For this purpose, four communication channels established through the modulation of white trichromatic LED emitters are used. Detection of the optical signals is performed with a photodiode based on two stacked pin structures made of a-Si:H and a-SiC:H. This device works as an optical filter in the visible spectrum and its spectral sensitivity can be adjusted through stationary optical bias. On-Off-Keying (OOK) modulation is used. The structure of the data blocks to be transmitted was designed to avoid undesirable effects related to ambient light (flickering and/or perceptible variations in color temperature of the white light). The experimental tests of the proposed model were performed using a small-scale prototype. The results show that with the proposed system it is possible to transmit information between road infrastructure and vehicles.  

This paper introduces the general editorial policy of i-ETC, a new online Open Access Journal. The publication of this academic journal is based on the software Open Journal System and it is maintained by the Department of Electronics, Telecommunications and Computer Engineering (DEETC), at the High Institute of Engineering of Lisbon (ISEL) in Lisbon.

The so called Internet of Things (IoT) is progressivelybecoming a normal thing in everyone daily lives. Thedesire of connecting everyday objects to the internet and to eachother, to interact with other users and machines, is increasinglybecoming a reality. In this context, where billions of connectedobjects are expected to be ubiquitously deployed worldwide, thefrequent battery maintenance of wireless nodes is undesirableor even impossible. The growth of the devices will be madepossible only if the sensors battery needs are eliminated orreduced significantly. For low power sensors and devices, carefulpower management and power conservation are critical to devicelifetime and effectiveness. One of the possible solutions is tochange completely the paradigm of the radio transceivers in thewireless nodes of the IoT system. The new paradigm should beable to communicate and to enhance the power to the sensor byusing only electromagnetic waveforms transmitted over the air,in order to make the Wireless Power Transfer (WPT) concept areality.

Today optical systems are more and more important in data communications (optical fibers) and are also becoming important in data processing (optical and quantum computing) allowing for a fully optical communication  network where all signals will be processed and transmitted in the optical domain. This paper gives an overview of optical fiber communications and analyses some optical devices and applications such as optical computing, holographic memory and optical pattern recognition.

This work presents an Inverted-L antenna design using the fractal geometry for dual band WLAN (2.4/5.2GHz) USB dongle application. The proposed antenna has the advantages of compact size, wide operation bandwidth and easy fabrication. The experimental results show that it has a S11<-10 dB bandwidth from 2.25 to 2.60 GHz and 5.06 to 5.62 GHz. The radiation performances of the proposed antenna in free space and when connected to a laptop computer were also studied in this work. The proposed antenna was designed and optimized by using Ansoft HFSS V13.

This paper describes an ECG signal coding with an adaptive predictive coding scheme using speech techniques like linear predictive coding and long-term prediction.

The sliding window dictionary-based algorithms of the Lempel-Ziv (LZ) 77 family are widely used for universal lossless data compression. The encoding component of these algorithms performs repeated substring search. Data structures, such as hash tables, binary search trees, and suffix trees have been used to speedup these searches, at the expense of memory usage. Previous work has shown how suffix arrays (SA) can be used for dictionary representation and LZ77 decomposition. In this paper, we improve over that work by proposing a new efficient algorithm to update the sliding window each time a token is produced at the output. The proposed algorithm toggles between two SA on consecutive tokens. The resulting SA-based encoder requires less memory than the conventional tree-based encoders. In comparing our SA-based technique against tree-based encoders, on a large set of benchmark files, we find that, in some compression settings, our encoder is also faster than tree-based encoders.

This paper presents the study of chirp signals for wireless communications between Internet of Thing devices used on low power wide area networks. Up and down chirp concept is introduced as well as the chirp spread spectrum concept. A computationally efficient symbol decoding method is presented based of discrete Fourier transform as an alternative to typical coherent detection. The proposed simulation LoRa model is implemented in MATLAB allowing the communication system evaluation based on bit error rate and packet error rate.

The modulation technique Filter Bank Multi Carrier (FBMC) is an alternative widely studied in order to replace Orthogonal Frequency Division Multiplexing (OFDM) in wireless telecommunications systems. The fact that FBMC does not use Cyclic Prefix and uses Polyphase Filters allows improvements in bit rate, bandwidth efficiency and robustness against multipath channel impairments. This implementation can bring advantages to Digital TV case in comparison to the traditional OFDM based systems because of the need to transmit higher resolution videos such as 4K and 8K. This article presents a study on the use of FBMC in Integrated System Digital Broadcasting Transmission B (ISDB-Tb), developing an application on GNURadio environment, analysing Bit Error Rate (BER) and power spectrum curves in a multipath channel.

This work describes the implementation of an eye gaze tracking system for a natural user interface, based only on non-intrusive devices, like Intel RealSense camera. Through image processing, the implemented system is able to convert face elements to the corresponding focus point on the computer screen. Tests show promising results.

ZnO 1-D nanostructures (nanowires) were deposited by a two-step wet chemical process. The dimensions of wires were about 100 nm - 1100 nm in length and about 20 - 120 nm in diameter. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) technique was used to obtain the microstructural information from the films. The nanowire films were also characterized optically by transmittance measurement and room temperature photoluminescence (PL) measurements. The transport properties of the samples were characterized by performing transient photoconductivity (TPC) experiments.

The ability to automatically detect/classify complex and dynamic urban sounds is important tool for urban planning such as building efficient noise monitoring and control, surveillance systems, urban soundscape mappings, and could be a foundation for improvement of life in the cities of tomorrow.We present a proof of concept for a sound detection, monitoring and classification system for urban environments in the context of Smart Cities. Ultimately, the proposed system be deployed in numerous urban locations for long periods of time, allowing for the collection of urban acoustic data.

This paper traces the theoretical background to the split between function and meaning in the modernity theories of Marx, Lukács, Weber and Marcuse. It then discusses attempts to overcome the split in the recent philosophies of technology of Simpson and Borgmann. These attempts fail but help to focus the issue. A discussion of contemporary struggles over information technology offers a more hopeful perspective on a possible resolution of the split and suggests a new look at Heidegger’s phenomenology of action. The conclusion of the paper shows that Heidegger offers resources for addressing the relation of function and meaning which he himself did not develop.