ESTGV - DEE - Documentos de congressos (comunicações, posters, actas)
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- High Energy OFDM Pulse Design Algorithm for Acoustic ToF Ranging and LocalizationPublication . Albuquerque, Daniel; Vieira, José; Lopes, Sérgio; Aguilera, Teodoro; Álvarez, FernandoThis paper proposes an algorithm to design band-limited Orthogonal Frequency Division Multiplexing (OFDM) pulses for accurate time-of-flight ranging in acoustic-based localization systems. The proposed algorithm is capable to generate OFDM pulses with higher energy when compared with other common pulse design approaches with similar characteristics. The results attained have shown that it is possible to design OFDM pulses with 17% more energy than a chirp or a BPSK pulse with the same characteristics. The proposed algorithm uses an iterative approach to increase the pulse energy while keeping the same amplitude, bandwidth and duration in each iteration. Two different OFDM pulses are provided and compared with two common pulses, namely chirp and BPSK pulses, with the same characteristics.
- TheremUS: the Ultrasonic ThereminPublication . Gomes, André; Albuquerque, Daniel; Campos, Guilherme; Vieira, JoséIn the Theremin, the performer’s hand movements, detected by two antennas, control the pitch and volume of the generated sound. The TheremUS builds on this concept by using ultrasonic sensing for hand position detection and processing all signals digitally, a distinct advantage in terms of versatility. Not only can different sound synthesis algorithms be programmed directly on the instrument but also it can be easily connected to other digital sound synthesis or multimedia devices; a MIDI interface was included for this purpose. The TheremUS also features translucent panels lit by controllable RGB LED devices. This makes it possible to specify sound-colour mappings in the spirit of the legendary Ocular Harpsichord by Castel.
- Application-Driven design to extend WSN lifetimePublication . Marques, Bruno; Ricardo, Manuelhe lifetime of a WSN depends on the energy of the nodes. As soon as nodes run out of energy, they get disconnected from the WSN. This paper proposes an Application Driven solution that increases the WSN lifetime by limiting the routing and forwarding functions of the network mainly to nodes running the same applications. The solution is evaluated against AODV, and the results obtained show gains of about 30%
- Improving the energy efficiency of WSN by using application-layer topologies to constrain RPL-defined routing treesPublication . Marques, Bruno F.; Ricardo, Manuel P.The deployment of thousands of tiny devices inter-networked together and accessible through the Internet is the result of the increasing trend towards enabling the concepts of Internet-of-Things. As these devices may be scattered in a unplanned way, a routing protocol is needed. The RPL protocol is the IETF proposed standard protocol for IPv6-based multi-hop Wireless Sensor Networks (WSN). RPL requires that communication paths go through a central router which may provide suboptimal paths, making no distinction of the applications the nodes run. To address these issues, an Application-Driven extension to RPL is proposed which enables the increase of the WSN lifetime by limiting the routing and forwarding functions of the network mainly to nodes running the same application. This paper evaluates the proposed solution coded in ContikiOS by means of Cooja simulations, and compares it against regular RPL. Simulation results confirm that the proposed solution provides lower energy consumption, lower end-to-end delays, and lower total number of packets transmitted and received.
- Monitoring system for small sized photovoltaic power plantsPublication . Correia, Daniel; Tomé, Paulo; Costa, Paulo Moisés; Marques, LuísThis paper presents a monitoring system devoted to small sized photovoltaic (PV) power plants. The system is characterized by: a high level of integration; a low cost, when compared to the cost of the PV system to be monitored; and an easy installation in the majority of the PV plants with installed power of some kW. The system is able to collect, store, process and display electrical and meteorological parameters that are crucial when monitoring PV facilities. The identification of failures in the PV system and the elaboration of performance analysis of such facilities are other important characteristics of the developed system. The access to the information about the monitored facilities is achieved by using a web application, which was developed with a focus on the mobile devices. In addition, there is the possibility of an integration between the developed monitoring system and the central supervision system of Martifer Solar (a company focused on the development, operation and maintenance of PV systems).
- Probabilistic Security Constrained Fuzzy Power Flow ModelsPublication . Gouveia, Eduardo; Costa, Paulo Moisés; Sagredo, Jesus; Soroudi, AlirezaIn restructured power systems, generation and commercialization activities became market activities, while transmission and distribution activities continue as regulated monopolies. As a result, the adequacy of transmission network should be evaluated independent of generation system. After introducing the constrained fuzzy power flow (CFPF) as a suitable tool to quantify the adequacy of transmission network to satisfy 'reasonable demands for the transmission of electricity' (as stated, for instance, at European Directive 2009/72/EC), the aim is now showing how this approach can be used in conjunction with probabilistic criteria in security analysis. In classical security analysis models of power systems are considered the composite system (generation plus transmission). The state of system components is usually modeled with probabilities and loads (and generation) are modeled by crisp numbers, probability distributions or fuzzy numbers. In the case of CFPF the component’s failure of the transmission network have been investigated. In this framework, probabilistic methods are used for failures modeling of the transmission system components and possibility models are used to deal with 'reasonable demands'. The enhanced version of the CFPF model is applied to an illustrative case.
- Flexible Power Control of Photovoltaic Plants Connected to Distribution NetworksPublication . Ribeiro, Susana; Costa, Paulo Moisés; Gouveia, Eduardo; Sousa, Pedro; Albuquerque, DanielThis paper presents a system to control the power injected by a photovoltaic (PV) plant on the receiving network. This control is intended to mitigate some of the negative impacts that these units may produce on such networks, while increasing the installed power of the plant. The controlled parameters are the maximum allowed value of injected active power and the corresponding power factor, whose setpoints values may be fixed or dynamic. The developed system allows a local and a remote control. The injected power and the corresponding power factor may be set by following a predetermined profile or by real time adjustments to fulfill specific operation constraints on the receiving network. The system acts by adjusting the control parameters on the PV inverters. The main goal of the system is, in the end, to control the PV plant, ensuring the accomplishment of technical constraints and, at the same time, maximizing the installed power of the PV plant, which may be an important issue concerning the economic performance of such plants
- The Smart Paradox : Stimulate the deployment of Smart grids with effective regulatory instrumentsPublication . Marques, Vítor; Bento, Nuno; Costa, Paulo MoisésThe concept of SG (Smart Grids) encompasses a set of technologies that raise the intelligence of the electrical networks, such as smart meters or instruments of communication, sensing and auto-correction of networks. Nevertheless, the cost is still an important obstacle for the transformation of the current electricity system into a smarter one. Regulation can have an important role in setting up a favorable framework that fosters investments. However, the novelty with SG is the disembodied character of the technology, which may change the incentives of the regulated network companies to invest, affecting the effectiveness of the regulatory instruments (“cost plus” or “price cap”). This paper demonstrates that the solution to this “Smart” paradox requires strong incentive regulation mechanisms able to stimulate the adoption of SG technologies. Moreover, the regulation should not jeopardize conventional investments that are unable to be substituted by SG. Thus, a combination of performance regulation and efficiency obligations may be necessary.
- Safe operation of transmission system considering EV at distribution levelPublication . Gouveia, Eduardo M.; Costa, Paulo Moisés; Sagredo, Jesus; Soroudi, AlirezaIn this paper, the IEEE 14 bus test system is used in order to perform adequacy assessment of a transmission system when large scale integration of electric vehicles is considered at distribution levels. In this framework, the symmetric/constr ained fuzzy power flow (SFPF/CFPF) was proposed. The SFPF/CFPF models are suitable to quantify the adequacy of transmission network to satisfy “reasonable demands for the transmission of electricity” as defined, for instance, in the European Directive 2009/72/EC. In this framework, electric vehicles of different types will be treated as fuzzy loads configuring part of the “reasonable demands”. With this study, it is also intended to show how to evaluate the amount of EVs that can be safely accommodated to the grid meeting a certain adequacy level.
- Architecture of Information System for Monitoring of Photovoltaic PlantsPublication . Pereira, António; Tomé, Paulo; Costa, Paulo Moisés; Pascoal, JoséThe monitoring and supervision systems are crucial to the operation of photovoltaic plants (PV), allowing the gathering of data about its operation. This data, after proper processing, allow to obtain performance indicators, the establishment of comparisons, the identification of behavior trends, the detection and location of malfunctions in equipment / systems and the definition of optimized maintenance plans. The most obvious consequence of the use of monitoring and supervision systems is the improvement of the technical and economical performance of PV plants. This article presents an architecture of a system able to provide information about the operation of a PV plant, regardless of its size, in a mobile device. The proposed architecture includes important aspects concerning the design of information systems, namely concerning the system flexibility and security.