Browsing by Author "Martins, R."
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- AUV Control and Communication using Underwater Acoustic NetworksPublication . Marques, E.; Pinto, J.; Kragelund, S.; Dias, P.; Madureira, L.; Sousa, A.; Correia, M.; Ferreira, H.; Gonçalves, R.; Martins, R.; Horner, D.; Healey, A. J.; Gonçalves, G.; Sousa, J. B.Underwater acoustic networks can be quite effective to establish communication links between autonomous underwater vehicles (AUVs) and other vehicles or control units, enabling complex vehicle applications and control scenarios. A communications and control framework to support the use of underwater acoustic networks and sample application scenarios are described for single and multi-AUV operation.
- Buildings Sustainability — The Non-Intrusive Load-Identification System ContributionPublication . Felgueiras, Carlos; Cruz, N.; Martins, F.; Martins, R.Buildings are responsible for an important share of the global energy consumed with the associated consequences at economic and environmental level. To overcome this actual concern several objectives were put in perspective, being one of them the energetic performance of systems and appliances. Efficiency depends on working on optimal conditions and user behavior. Monitoring of the energy consumption of each electric load is important but the use of decentralized energy is not feasible at present due to the huge number of loads connected to the electric grid. An alternative consists on the use of a centralized measurement device able to identify loads. This work presents a measurement infrastructure that have, among others, the possibility to make the identification of electrical loads data will be used to improve the energetic performance of households and buildings and increase the sustainability of the energy system.
- Embedded Electricity Quality AnalyzerPublication . Freitas, S.; Martins, R.; Martins, F.; Felgueiras, CarlosElectric installations are traditionally designed for supplying an electric service. The only one associated instrument is the energy meter that is introduced only for measure the total amount of energy that will be charged to the user. However, the exploration of parameters associated with electricity can provide several advantages such the household performance devices, legal issues and later one a more sustainable way to use the electricity energy. This work presents the principle of a low cost energy analyzer that will be part of an electric home installation. Electric parameters are measured and then transmitted via Wi-Fi to a domestic server where all data are stored. This data exploitation can be later one used for several purposes, since electric efficiency to electric charges prediction.
- Low torque loss gears: austempered ductile iron versus carburized steelPublication . Magalhães, Luís; Martins, R.; Seabra, Jorge; Gonçalves, R.Low-loss power transmission gears operate at lower temperature than conventional ones because their teeth geometry is optimized to reduce friction. The main objective of this work is to compare the operating stabilization temperature and efficiency of low-loss austempered ductile iron (ADI) and carburized steel gears. Three different low-loss tooth geometries were adopted (types 311, 411 and 611, all produced using standard 20° pressure angle tools) and corresponding steel and ADI gears were tested in a FZG machine. The results obtained showed that low-loss geometries had a significant influence on power loss, gears 611 generating lower power loss than gears 311. At low speeds (500 and 1000 rpm) and high torque ADI gears generated lower power loss than steel gears. However, at high speed and high torque (high input power and high stabilization temperature) steel gears had better efficiency.
- Low-loss austempered ductile iron gears: experimental evaluation comparing materials and lubricantsPublication . Magalhães, Luís; Martins, R.; Seabra, JorgeAn experimental study to evaluate the power dissipation of gears was performed. Three low-loss gear models were manufactured using standard 20° pressure angle tools. Austempered ductile iron (ADI) and 20MnCr5 carburized steel gears were tested in an FZG gear test machine using mineral, ester and polyalphaolephine (PAO)-based oils. The results compare power dissipation, the influence of different tooth flank geometries, materials and lubricants. This work concludes that conventional power-transmission gears can be replaced by these improved and more efficient low–loss models, which can be produced using common tools and that steel gears can be successfully replaced by austempered ductile iron gears.
- Marine Operations with the SWORDFISH Autonomous Surface VehiclePublication . Ferreira, Hugo; Martins, R.; Marques, E.; Pinto, J.; Martins, A.; Almeida, J. M.; Sousa, J. B.; Silva, E. P.This paper describes the design and development of the Swordfish Autonomous Surface Vehicle (ASV) system. The work focuses the sensors, actuators, communications and C4I of an unmanned vehicle for marine operations. SWORDFISH is an autonomous surface vehicle used as the central communications link between air, undersea, and terrestrial robotic vehicles of a network centric operation. It is used as a test bed platform for deployment and testing of advanced control and operational concepts for multi-vehicles systems. This new unmanned marine vehicle was done in the context of the PISCIS project. The PISCIS project concerns the development, test and evaluation of new vehicles and new concepts of operation for networked vehicle systems in oceanographic data collection. The PISCIS system includes two autonomous underwater vehicles, the Swordfish ASV, an acoustic navigation system, acoustic and radio communications and a distributed command and control system.
- Swordfish: an Autonomous Surface Vehicle for Network Centric OperationsPublication . Ferreira, H.; Martins, R.; Marques, E.; Pinto, J.; Martins, A. O.; Almeida, J. M.; Sousa, J. B.; Silva, E. P.The design and development of the swordfish autonomous surface vehicle (ASV) system is discussed. Swordfish is an ocean capable 4.5 m long catamaran designed for network centric operations (with ocean and air going vehicles and human operators). In the basic configuration, Swordfish is both a survey vehicle and a communications node with gateways for broadband, Wi-Fi and GSM transports and underwater acoustic modems. In another configuration, Swordfish mounts a docking station for the autonomous underwater vehicle Isurus from Porto University. Swordfish has an advanced control architecture for multi-vehicle operations with mixed initiative interactions (human operators are allowed to interact with the control loops).