i-ETC : ISEL Academic Journal of Electronics Telecommunications and Computers
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ELECTROSPINNING PAN/PdCl2 NANOFIBER FOR HIDROGEN STORAGE – THE INFLUENCE OF THE PREPARATION METHOD
No full textThe search for materials for hydrogen storage that are able to adsorb and desorb hydrogen molecules has received attention. Nanofibers have been studied because it has some interesting characteristics like high surface to volume ratio and the ease of producing by means of a low-cost setup. Polyacrylonitrile (PAN) has allowed the possibility of obtaining carbon nanofibers from the electrospinning process followed by a thermal treatment; moreover Pd has the capability of store hydrogen and can form a complex with dimethylformamide (DMF) so that, during the preparation of the solution of PAN and PdCl2, both present high solubility in the solvent. Thus, the results demonstrated that as Pd can form complex with DMF the preparation method of the PAN+PdCl2 solutions influences the interaction between Pd and PAN. The decrease in dispersion viscosity and an unexpected increase in the diameter of the fibers confirm the hypothesis. The FTIRS and XPS analysis confirm that the Pd complexes with DMF by means of bonds to N
A primer on understanding Google Earth Engine APIs
Full text linkThis 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
ElectroGes - a Household IoT Energy Management System
Full text linkDomestic appliances plugged to the electrical mains power may, at some point, exceed the maximum contracted power supplied from the electrical company. To avoid a power cut-off on these cases, an energy management system is needed so that some appliances are automatically switched off before others are switched on. In order to do this, appliances have to be described in a privileged structure so that power is always available for some of them while other share leftovers. ElecroGes is a system that provides the house owner with a means to define the priorities of the connected appliances and manage them in an autonomous way; a working implementation is provided
VLC system for the determination of a vehicle’s position and speed
Full text linkIn 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.
Stochastic Theater: Stochastic Datapath Generation Framework for Fault-Tolerant IoT Sensors
Full text linkStochastic Computing has emerged as a competitive computing paradigm that produces fast and simple implementations of arithmetic operations, while offering high levels of parallelism, and graceful degradation of the results when in the presence of errors. IoT devices are often operate under limited power and area constraints and subjected to harsh environments, for which, traditional computing paradigms struggle to provide high availability and fault-tolerance. Stochastic Computing is based on the computation of pseudo-random sequences of bits, hence requiring only a single bit per signal, rather than a data-bus. Notwithstanding, we haven’t witnessed its inclusion in custom computing systems. In this direction, this work presents Stochastic Theater, a framework to specify, simulate, and test Stochastic Datapaths to perform computations using stochastic bitstreams targeting IoT systems. In virtue of the granularity of the bitstreams, the bit-level specification of circuits, high-performance characteristics and reconfigurable capabilities, FPGAs were adopted to implement and test such systems. The proposed framework creates Stochastic Machines from a set of user defined arithmetic expressions, and then tests them with the corresponding input values and specific fault injection patterns. Besides the support to create autonomous Stochastic Computing systems, the presented framework also provides generation of stochastic units, being able to produce estimates on performance, resources and power. A demonstration is presented targeting KLT, typical method for data compression in IoT applications
Passive Optical Communications Module for the Internet of Things
Full text linkThe 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
Self-Optimization of Low Coverage and High Interference in Real 3G/4G Radio Access Networks
Full text linkThis paper presents a new single cell multi-objectiveoptimization algorithm. The objective is to optimize areas oflow coverage and high interference simultaneously, through theadjustment of the antenna tilts and/or antenna orientation. Theprocess is achieved using a specific implementation of a ParticleSwarm Optimization (PSO) algorithm. Both the detection ofsub-optimal performance areas and its subsequent optimizationare supported by Drive Test (DT) data and network topologyinformation. The antenna optimization algorithm was tested withreal data in 3rd Generation (3G)/4th Generation (4G) networks.In this work, a 3G urban scenario is highlighted, achieving anaverage optimization gain of 78%
On the Feasibility of GPON Fiber Light Energy Harvesting for the Internet of Things
Full text linkThe emerging concept of smart cities demands for a large number of electronic devices, like sensors and actuators, distributed over several public spaces and buildings. The Internet of Things (IoT) has a key role in connecting devices to the Internet. However, the significant number of devices makes the maintenance task of the entire network difficult and expensive. To mitigate this problem, considerable research efforts have been made to develop energy-aware devices capable of self-sustainable operation, by harvesting their energy from various sources. In this paper, we study the possibility of harvesting energy from the light flowing in the Gigabit Passive Optics Network (GPON) to supply low-power devices. Since most cities already have a working GPON installation, using this installation to interconnect and power IoT devices can be a viable and less expensive solution, instead of installing new dedicated networks. This is also an interesting solution to convey communications and energy to low-power applications where access to the power grid is unfeasible. This study is focused in the 1550 nm wavelength, whose available optical power, in residential premises, is between -7 dBm and +2 dBm. With this range of optical power, and with a 30% efficiency photodiode, we show, for the worst-case scenario of the GPON, how it is possible to harvest 62 µW of energy at the Maximum Power Point (MPP)
BlueLab IoT, a Universal Software Platform for IoT Data Acquisition Devices
Full text linkPhysical devices with different sensors and sampling rates distributed over several unrelated locations need to store their values over time. Applications that need the result of a set of sensors must access their data. A common and simple interface within the physical devices, monitoring stations, to store data on a database is needed; as also a simple and common retrieval interface for any application that only shows the data as it is or processes it into higher levels of significance. BlueLab IoT is a platform with libraries and an interface application to aid that development; a working implementation is provided
Autonomic Function Evaluation in an Intermittent Lead Exposure Animal Model
Full text linkLead (Pb) is a toxic metal, which widespread use has resulted in environmental contamination, human exposure and significant public health problems. The autonomic nervous system, being a homeostatic controller, is impaired in acute and chronic lead exposure. In fact, sympathoexcitation associated to hypertension and tachypnea has been described together with baroreflex and chemoreflex dysfunction. However, up to date, no studies described the autonomic effects of an intermittent low-level lead exposure. In the present work, we addressed in vivo, autonomic behaviour in rats under chronic Pb exposure (control) and in rats under intermittent Pb exposure. For that, arterial blood pressure (BP) and ECG were recorded in 28 weeks old animal and low frequencies (LF) and high frequencies (HF) were determined (to estimate sympathetic and parasympathetic activities) using FisioSinal software with Wavelet module. Preliminary results: Rats intermittently exposed to lead showed a significant decrease in systolic BP (126 ± 4 vs 144 ± 3 mmHg) with no significant changes in LF, HF and LF/HF bands (1.5 ± 0.3 vs 1.7 ± 0.5 mmHg2, 1.9 ± 0.7 vs 2.8 ± 1.2 bpm2 and 1.2 ± 0.4 vs 1.1 ± 0.3 mmHg2/bpm2, respectively) when compared to chronically Pb exposed rats. Our data suggests that the autonomic dysfunction induced by lead exposure is similar in a chronic and intermittent Pb exposure. Nevertheless, it seems that an intermittent exposure was no effect on systolic BP values.The present study brings new insights on the environmental factors that influence autonomic and cardiovascular systems during development, which can help apprise public policy strategies to prevent and control the adverse effects of Pb toxicity