INESCC-DL - Artigos em Livros de Actas
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- Accuracy versus complexity of MARG-based filters for remote control pointing devicesPublication . Rasteiro, Miguel ; Costelha, Hugo; Conde Bento, Luis; Assunção, PedroAlthough most current pointing devices rely on relative rotation increments, absolute orientation allows for a more intuitive interaction. However, this is difficult to implement in low-energy consumption devices since accurate fusion filters are computationally intensive. This work presents a comparative study of low-complexity filters and state-of-the-art orientation tracking systems, enabling to access complexity versus portability. A relevant set of different MARG units currently available on the market were studied under systematic tests and human subjective user analysis. Experimental results show that it is possible to obtain similar accuracy using low-complexity filters to the ones observed with state-of-the-art orientation tracking systems. © 2015 IEEE.
- A comparison of the vibration characteristics of a rotating machine with a linear and a keyed shaftPublication . Oliveira, F.; Pelaez, G.; Donsion, M. P.This paper presents some results of an ongoing work aimed at studying a number of characteristics of rotating machines and how they are influenced by both constructive features and the way they are driven. The following will present the main results obtained when a simple one-stage inertia turbomachine is built with a linear, cylindrical shaft or, instead, with a shaft that has a small slot such as those used in many mechanical couplings. Experimental results will show some significant differences in the behavior of the machine, both in terms of the orbit and in the resonance frequencies, as well as in the phase and amplitude of mechanical vibrations.
- Complexity Analysis of a Business Process Automation: Case Study on a Healthcare OrganizationPublication . Martinho, Ricardo; Rijo, Rui, Rui Pedro Charters Lopes; Nunes, AnaHealthcare organizations have been struggling to get Business Process Management (BPM) and associated Information and Communication Technologies (ICT) properly aligned to improve their patients' service and quality of care. Nevertheless, the highly structured nature of larger organizations such as hospitals hampers this alignment, and commonly ICT is applied to isolated tasks or fragments of processes. In this paper, we present and discuss the results, in terms of complexity, of the introduction of a new scheduling system within the medical appointment and exam business processes of a large hospital. During the case study, we began by modelling the processes using the Business Process Modelling and Notation (BPMN) standard. We then used abstract metrics to compare the complexity between old (before the introduction of the scheduling system) and new processes, and interpreted the obtained results. Finally, we derived important conclusions that will help guide us in further business process optimization endeavors.
- Diffusion and distribution of touristic routes: Web platform's architecture on tourism contextPublication . Hugo Miguel Pereira Chambel; Pereira, António Manuel de JesusIn this document it will be described the architecture of an information system that was originated in an innovative idea based roots in joining two milestones of the social environment, tourism and technology. Separating the components then it will be described tourism, represented by tourism regions and the technology that allows navigation in small footpaths using Android mobile devices, which result on support of information and communication technologies to tourism and regions themselves.
- DOTS: Drift Oriented Tool SystemPublication . Antunes, Mário; Costa, Joana; Silva, Catarina; Bernardete RibeiroDrift is a given in most machine learning applications. The idea that models must accommodate for changes, and thus be dynamic, is ubiquitous. Current challenges include temporal data streams, drift and non-stationary scenarios, often with text data, whether in social networks or in business systems. There are multiple drift patterns types: concepts that appear and disappear suddenly, recurrently, or even gradually or incrementally. Researchers strive to propose and test algorithms and techniques to deal with drift in text classification, but it is difficult to find adequate benchmarks in such dynamic environments. In this paper we present DOTS, Drift Oriented Tool System, a framework that allows for the definition and generation of text-based datasets where drift characteristics can be thoroughly defined, implemented and tested. The usefulness of DOTS is presented using a Twitter stream case study. DOTS is used to define datasets and test the effectiveness of using different document representation in a Twitter scenario. Results show the potential of DOTS in machine learning research.
- eServices - Service Platform for Pervasive Elderly CarePublication . Marcelino, Isabel; Laza, Rosalía; Domingues, Patrício; Gómez-Meire, Silvana; Pereira, AntónioIn this paper, we present a solution to improve elderly’s quality of life. eServices – Service platform for pervasive elderly care was designed to aggregate several services developed to meet senior population’s needs. It monitors basic life signs, environment variables and uses personal location technology. Besides sensor services, eServices solution contains digital services align with emotional and social care needs. Due to target population specifications, eServices was designed to be as simple and accessible as possible in order to remove technological barriers. One of eServices major features is to detect imminent danger situations, act accordingly. It also collects the data from the sensors, location routines and from the interactions between the elderlies and the provided services to detect behavior deviations in order to act preventively. The platform was tested by seniors in real scenario. The experimental results demonstrated that the proposed platform was well accepted and easy to use by seniors, which demonstrated enthusiasm and interest in daily bases use.
- An Evolutionary Algorithm based on an outranking relation for sorting problemsPublication . Oliveira, Eunice; Antunes, Carlos HenggelerA new approach for using the preferences elicited from a Decision Maker (DM) into the operational framework of an Evolutionary Algorithm (EA) is presented. The preference representation is achieved using the parameters and principles of the ELECTRE TRI method devoted to the sorting problem. The outranking relation is used to replace the non-dominance relation in the usual operators in the EA (crossover, mutation and selection operator). The aim of this approach is to focus the search on the region of interest defined by the DM's preferences and consequently restrict the number of solutions in the Pareto-optimal front to be subject to further screening. This aspect is particularly important when dealing with problems that lead to a large number of non-dominated solutions.
- A hybrid multi-objective GRASP+SA algorithm with incorporation of preferencesPublication . Oliveira, Eunice; Antunes, Carlos Henggeler; Gomes, ÁlvaroA hybrid multi-objective approach based on GRASP (Greedy Randomized Adaptive Search Procedure) and SA (Simulated Annealing) meta-heuristics is proposed to provide decision support in a direct load control problem in electricity distribution networks. The main contributions of this paper are new techniques for the incorporation of preferences in these meta-heuristics and their hybridization. Preferences are included in the construction phase of multi-objective GRASP, in SA, as well as in the selection of solutions that go to the next generation, with the aim to obtain solutions more in accordance with the preferences elicited from a decision maker. The incorporation of preferences is made operational using the principles of the ELECTRE TRI method, which is based on the exploitation of an outranking relation in the framework of the sorting problem.
- Influence of a SVC on AC Arc furnaces harmonics, flicker and unbalance. Measurement and analysis.Publication . Donsión, M. P.; Güemes, J. A.; Oliveira, F.An AC arc furnace is an unbalanced, nonlinear and time varying load, which can cause many problems to power system quality. Different studies on arc furnaces harmonics analysis can be found in the bibliography on the topic; however, it is very difficult obtain an exact model that takes into account all the parameters that have influence on the process, therefore it is necessary to take measurements under different conditions. In this paper we'll present the harmonic distortion, flicker and unbalance results and conclusions on three different measurement campaigns in an iron and steel industry (SNL) with an AC arc furnace of 83 MW (170 TM) with a transformer of 120 MVA connected with a dedicated power line of 220 kV (55 km) to the Carregado Substation, where there are another other branches that connect industrial and domestic consumers.
- On the information provided by uncertainty measures in the classification of remote sensing imagesPublication . Gonçalves, Luisa; Fonte, Cidália C.; Júlio, Eduardo N.B.S.; Caetano, MarioThis paper investigates the potential information provided to the user by the uncertainty measures applied to the possibility distributions associated with the spatial units of an IKONOS satellite image, generated by two fuzzy classifiers, based, respectively, on the Nearest Neighbour Classifier and the Minimum Distance to Means Classifier. The deviation of the geographic unit characteristics from the prototype of the class to which the geographic unit is assigned is evaluated with the Un non-specificity uncertainty measures proposed by [1] and the exaggeration uncertainty measure proposed by [2]. The classifications were evaluated using accuracy and uncertainty indexes to determine their compatibility. Both classifications generated medium to high levels of uncertainty for almost all classes, and the global accuracy indexes computed were 70% for the Nearest Neighbour Classifier and 53% for the Minimum Distance to Means Classifier. The results show that similar conclusions can be obtained with accuracy and uncertainty indexes and the latter, along with the analysis of the possibility distributions, may be used as indicators of the classification performance and may therefore be very useful tools. Since the uncertainty indexes may be computed to all spatial units, the spatial distribution of the uncertainty was also analysed. It's visualization shows that regions where less reliability is expected present a great amount of detail that may be potentially useful to the user.