Search results for "Simulation."
showing 10 items of 4779 documents
Android tool to evaluate grounding resistance
2015
In the absence of sources of rapidly varying field, the study of the potential distribution determined, in a linear medium, by a geometrically complex grounding may be conducted by applying the method of superposition of the effects, known as method of subareas of Maxwell. Such approach can be usefully employed in an educational tool intended for students of electrical engineering.
Safety Concerns on Ground Fault Application Transfer Phenomenon in HV Installations
2007
When a fault to ground occurs in HV/MV substations supplied by a combined overhead-cable line, most of the fault current can be transferred and injected into the soil several kilometers far away from the fault location. This phenomenon is called "fault application transfer" and mostly concerns transition stations, where cables are connected to the overhead line. If the transition station is a dead-end steel pole structure, usually accessible to the general public, the local ground electrode could be inadequate to maintain ground potential rise within safety limits. Hence, dangerous touch and step voltages may appear at exposed locations. In the paper results of various computer simulations …
Modeling Alternatives Sustainable-Energy-Policy for the Supply Chain of Wind Power in Brazil.
2020
Renewable energy studies have received high attention in the last few years due the increasing deployment of alternatives such as wind, solar and biomass, as a result of the urgency in reducing fossil fuels consumption. This situation has involved an important challenge for long-term renewables policy and energy system planning. Brazil is the richest country in terms of renewable sources in Latin American. Brazil has energy generation portfolio not much different form the Colombia one, and the understanding of this very important country will contribute to inspire other countries in the region, particularly Colombia. Since 2004 the Brazilian energy policy promotes wind power development aim…
Fixed speed wind turbine generator model validation and dynamic simulation using Matlab/Simulink
2007
In the last two decades an increasing amount of electricity has been generated from renewable sources in order to mitigate the environmental impact of the conventional power plants. In the next future wind turbines may affect the behaviour of electrical power system. This paper describes the model of a typical fixed speed wind turbine connected to the grid; the model is developed in the simulation tool Matlab/Simulink. It’s composed by the aerodynamic system, the shaft model (two-mass system), the induction generator (fifth order model) and the stall control system of the wind turbine rotor. The validation of the wind turbine model is made in steady-state operation, and the results are veri…
Non-uniform doping concentration CIGS absorber profile for highefficiency solar cells
2016
The quaternary chalcopyrite semiconductor alloy Cu(In,Ga)Se2 (CIGS) is nowadays commonly considered one of the most suitable materials to fabricate cost-effective and high-efficiency photovoltaic cells. Thanks to the optical and structural properties of the absorber layer and to the tunable bandgap, thin-film CIGS cells have reached efficiencies around 20%, not far from the maximum values of traditional crystalline silicon cells. This high efficiency, together with the conceivable low fabrication costs, makes CIGS cells a promising alternative to silicon technology for large-scale production. In order to further improve the cells performance, in a previous work we have already proposed a si…
Cross-Technology WiFi/ZigBee Communications: Dealing With Channel Insertions and Deletions
2016
In this letter, we show how cross-technology interference can be exploited to set up a low-rate bidirectional communication channel between heterogeneous WiFi and ZigBee networks. Because of the environment noise and receivers' implementation, the cross-technology channel can be severely affected by insertions and deletions of symbols, whose effects need to be taken into account by the coding scheme and communication protocol.
Constant Heat Input Friction Stir Welding of Variable Thickness AZ31 Sheets Through In-Process Tool Rotation Control
2019
Tailored blanks characterized by variable thickness were friction stir welded (FSWed) with the aim to obtain constant joint properties along the weld seam, regardless of the thickness change. To pursue this goal, the heat input was kept constant by in-process control of tool rotation. A dedicated numerical model of the process was used to determine the tool rotation values as a function of the sheet thickness. The mechanical properties and the microstructure of the FSWed joints, produced with varying process parameters, were studied. It was found that the proposed approach can produce joints with uniform properties along the weld line in terms of stress–strain curve shape, joint strength, e…
A Platform for the Evaluation of Distributed Reputation Algorithms
2018
In distributed environments, where unknown entities cooperate to achieve complex goals, intelligent techniques for estimating agents' truthfulness are required. Distributed Reputation Management Systems (RMSs) allow to accomplish this task without the need for a central entity that may represent a bottleneck and a single point of failure. The design of a distributed RMS is a challenging task due to a multitude of factors that could impact on its performances. In order to support the researcher in evaluating the RMS robustness against security attacks since its beginning design phase, in this work we present a distributed simulation environment that allows to model both the agent's behaviors…
Adaptable data models for scalable Ambient Intelligence scenarios
2011
In most real-life scenarios for Ambient Intelligence, the need arises for scalable simulations that provide reliable sensory data to be used in the preliminary design and test phases. This works present an approach to modeling data generated by a hybrid simulator for wireless sensor networks, where virtual nodes coexist with real ones. We apply our method to real data available from a public repository and show that we can compute reliable models for the quantities measured at a given reference site, and that such models are portable to different environments, so as to obtain a complete, scalable and reliable testing environment.
SmartBuildings: An AmI system for energy efficiency
2015
Nowadays, the increasing global awareness of the importance of energy saving in everyday life acts as a stimulus to provide innovative ICT solutions for sustainability. In this scenario, the growing interest in smart homes has been driven both by socioeconomic and technological expectations. One of the key aspects of being smart is the efficiency of the urban apparatus, which includes, among others, energy, transportation and buildings. The present work describes SmartBuildings, a novel Ambient Intelligence system, which aims at reducing the energy consumption of "legacy" buildings by means of artificial intelligence techniques applied on heterogeneous sensor networks. A prototype has been …