ESTG - Comunicações em conferências e congressos internacionais
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- A new diagnostic technique for real-time diagnosis of power converter faults in switched reluctance motor drivesPublication . Marques, Jorge F.; Estima, Jorge O.; Gameiro, Natália S.; Cardoso, A. J. MarquesAccurate fault identification allows the adoption of procedures that minimize the fault impact on the machines operation. Switched reluctance motors (SRMs) have been recognized for their fault-tolerant capabilities and they present a very robust configuration, particularly due to the absence of windings or magnets in the rotor. All these attributes make the SRM a competitive solution for aircraft and automotive applications, where systems reliability is a crucial feature. Therefore, in this paper, a new algorithm for real-time diagnosis of power converter faults in SRM drives is proposed. In contrast to other methods that use additional sensors or devices, the presented technique uses the measured phase currents only, which are already available for the drive control. The proposed algorithm effectively detects the inverter faulty phase and is capable to localize the faulty power switch. Power switch open-and short-circuit fault occurrences in an asymmetric full-bridge converter are considered and analyzed.
- Soluções SIEM open source: um estudo comparativoPublication . Vazão, Ana; Santos, Leonel; Piedade, Maria Beatriz; Rabadão, CarlosOs ataques informáticos estão a aumentar de complexidade e de número de ocorrências, tornando primordial implementar ferramentas como o Security Information and Event Management (SIEM) para mitigar os riscos, uma vez que as Organizações dependem cada vez mais dos sistemas informáticos para o desenvolvimento das suas atividades. O presente trabalho compara várias soluções SIEM open source, recorrendo à pesquisa bibliográfica e à implementação de vários cenários de testes, com o objetivo de criar um protótipo e de efetuar a avaliação do mesmo em contexto de produção. A solução escolhida vai ter de ter em consideração as exigências legais do Regulamento Geral de Proteção de Dados, como é o caso da anonimização e da pseudoanonimização dos dados sensíveis, o tempo de retenção dos logs e a sua encriptação.
- A Hybrid Application for Real-Time Air Quality MonitoringPublication . Silva, Jorge; Salgueiro, Pedro; Rato, Luis; Saias, José; Nogueira, Vitor; Lucas, Pedro; Araujo, Filipe; Silva, Catarina; Gil, Paulo; Cardoso, Alberto; Arrais, Joel; Ribeiro, Bernardete; Coutinho, DanielWith the raising concerns for the environment, interest in monitoring air quality is likely to increase in the near future. However, most data comes from a limited number of government-owned sensors, which can only capture a small fraction of reality. Improving data coverage thus involves reducing the cost of sensors and make data widely available. For this, we will use a very high number of low-cost sensors as the basis for an air quality monitoring platform, capable of collecting, aggregating, storing and displaying data. This platform will use stream-based technologies capable of scaling for large numbers of sensors and users. The resulting NanoSen-AQM platform will provide vast amounts of air quality data to the public, with the aim of improving public health.
- CoAP Flow Signatures for the Internet of ThingsPublication . Canuto, Luis; Santos, Leonel; Vieira, Leandro; Goncalves, Ramiro; Rabadão, CarlosThe development of technology brought an exponential evolution of IoT networks, and with a number of different devices connected to the Internet, meaning, more IP addresses, traffic and devices susceptible to attacks. These types of networks are characterized by their interoperability and low resources, making it a complex ecosystem and making it difficult to implement management and monitoring measures, leading to a lack of security. Considering the impact that IoT networks have on the market, their protection is essential and, is now one of the themes in constant evolution. With the focus on security, this work aims to characterize a CoAP and CoAPS signatures, through the analysis of a flow in a test scenario and recognize the types of messages of the signature and what is their impact on the network and later creating rules that could help an IDS, in order to save resources and time. When analyzing the flows, it was concluded that it is possible to identify some characteristics of a signature, such as identifying Confirmable and Non-Confirmable messages.
- Multi-scale computer simulations of multi-tubular components manufactured by water-assisted injection mouldingPublication . Pascoal-Faria, Paula; Alves, Nuno; Kamma-Lorger, Christina S.; Marques, Rita; Gomes, Marta; Venkat, Anurag; Silva, Rui; Bastos, Lourenço; Carneiro, Filipa; Cunha, Jorge; Mateus, Artur; Mitchell, Geoffrey R.Water assisted injection moulding is a recent development in the manufacturing technology associated with injection moulding. Injection moulding involved the high pressure injection of molten plastic in to a preformed metal mould which defines the exterior of the shape of the object. Water assisted injection moulding is a variant with an addition step in which water is injected into the mould after its has been filled with molten plastic. The water jet sweeps out the molten plastic in its path to leave a hollow tube in which the interior of the part is defined by the water jet. This technology is used for preparing tubular components for use in the automotive industry and for domestic appliances. We have been developing the technology to prepare parts with branches in the tubing. We have used fine-element simulations to explore the relationship between the process parameters and the subsequent final part. Of course such simulations only serve to define the exterior and interior of the tubular part. It is clear from the outline of the technology above that the molten plastic is subjected to a complex pressure and temperature variation with time which vary across the part and its location within the mould. The specification of the part is in most cases is limited to the geometry and the materials which is used in its preparation, in this case polyamide6 with 30% glass fibre. From the development of plastic processes over the last 50 years we have learnt that the properties of plastic part depend critically on the processing pathway and in particular the timescale for the transformation from molten material to the semi-crystalline solid state. We know from the use of small-angle and wide-angle scattering mapping of the structure and morphology of the multi-tubular components that the level of crystallinity and the extent of preferred orientation varies throughout the part and this may lead to warpage and other geometrical changes in the part during its service life. We have set out to explore how we can use the temperature and pressure variation from the finite element modelling to predict the structure and morphology at different regions in the part in order to be able to establish the parameters which yield a geometrically correct part which is also homogenous in its structure and morphology and hence properties. This paper describes the approach we have taken to make progress with this complex matter of simulations on multiple scales and the application of this technique to realistic automotive tubular components.
- Data warehousing in the context of a Bologna undergraduate degreePublication . Ramos, José Vitor; Rui OliveiraFacing the incessant growth of data that organizations have to deal with on a daily basis, decision support systems and data warehousing techniques assume a vital importance in supporting the decision making process. Taking this necessity in consideration, the Bologna process was an opportunity to introduce data warehousing competences in the undergraduate degree of Informatics Engineering at Polytechnic Institute of Leiria (IPL). The paper focus some aspects related with this adaptation, the difficulties and challenges during the implementation process and the solutions adopted, towards an effective acquisition of competences by students.
- A hybrid evolutionary simulated annealing algorithm with incorporation of preferencesPublication . Oliveira, Eunice; Antunes, Carlos Henggeler; Gomes, ÁlvaroThis paper presents a hybrid evolutionary simulated annealing approach devoted to multi-objective models, in which preferences are elicited and exploited using the principles of the outranking-based ELECTRE TRI method. Preferences are used to guide the search process including deciding about the exploitation of new neighbor solutions. The overall approach has been used in a case study to provide decision support in identifying suitable load control actions in electrical networks.
- Mobile application development process: A practical experiencePublication . Ghandi, Lizeth; Silva, Catarina; Martinez, Danilo; Gualotuna, TatianaNowadays there is an increasing interest in mobile application development. However, developers often disregard, or at least significantly adapt, existing software development processes to suit their purpose, given the existing specific constraints. Such adjustments can introduce variations and new trends in existing processes that in many occasions are not shared with the scientific community since there is no official documentation, thus justifying further research. In this paper, we present a study and characterization of current mobile application development processes based on a practical experience. We consider a set of real case studies to investigate the current development processes for mobile applications used by software development companies, as well as by independent developers. The result of the present study is the identification of mobile software development processes, namely agile approaches, and also of shortcomings in current methodologies applied in industry and academy, namely the lack of informed and experienced resources to develop mobile apps.
- 3D video shot boundary detection based on clustering of depth-temporal featuresPublication . Ferreira, Lino; Assunção, Pedro; Cruz, Luis A. da SilvaThis paper proposes an algorithm for automatic detection of 3D video shots with different perceptual features. The proposed algorithm is able to identify distinct three-dimensional visual scenes by detecting 3D video shot boundaries based on clustering of depth-temporal features. A combination of texture variation along the temporal dimension and depth variance is used by K-means clustering to find the stereo frames which comprised the 3D scene boundaries. An important characteristic of the proposed algorithm in comparison with others published in the literature for temporal segmentation of classic 2D video is that no thresholds are used in the decision processes neither training data sets. The experimental results show that the proposed method is capable of achieving high recall (e.g., 0.95) and precision rate (e.g., 1.0) in video sequences with both sharp and smooth 3D scene transitions.
- Video compression using 3D multiscale recurrent patternsPublication . Francisco, Nelson C.; Rodrigues, Nuno M. M.; Silva, Eduardo A. B. da; Carvalho, Murilo B. de; Faria, Sergio M. M. deIn this paper, we propose a new 3D pattern matching based video compression algorithm. Spatiotemporal prediction tools are used to exploit both the temporal and the spatial redundancies, and the resulting residue is encoded using a 3D data coding extension of the Multidimensional Multiscale Parser (MMP) algorithm. MMP was originally proposed as a generic lossy data compression algorithm. A high degree of adaptivity and versatility allowed it to be competitive with state-of-the-art transform-based compression methods for a wide range of applications and data sets. The performance of the proposed algorithm is compared with that of H.264/AVC, achieving close results for some data sets, which indicates the potential of the pattern matching paradigm as an alternative to the traditional hybrid video codecs.