ESTGV - DI - Artigo em revista científica, indexada ao WoS/Scopus
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- From periodic to chaotic oscillations in composite laminated platesPublication . Ribeiro, P.; P. Duarte, RuiThe geometrically non-linear, linear elastic, oscillations of composite laminated plates are studied in the time domain by direct numeric integration of the equations of motion. A p-version finite element, where first-order shear deformation is followed and that was recently proposed for moderately thick plates, is employed to define the mathematical model. By applying transverse harmonic forces, the variation of the oscillations with the angle of the fibres is investigated. With this kind of excitation, only periodic motions with a period equal to the one of the excitation are found. However, introducing in-plane forces, m-periodic or quasi-periodic oscillations, as well as chaotic oscillations are computed. The existence of chaos is confirmed by calculating the largest Lyapunov exponent.
- Trust and reputation management for critical infrastructure protectionPublication . Caldeira, Filipe; Monteiro, Edmundo; Simões, PauloToday’s critical infrastructures (CIs) depend on information and communication technologies (ICTs) to deliver their services with the required level of quality and availability. ICT security plays a major role in CI protection and risk prevention for single and also for interconnected CIs were cascading effects might occur because of the interdependencies that exist among different CIs. This work addresses the problem of ICT security in interconnected CIs. Trust and reputation management using the policy-based management paradigm is the proposed solution to be applied at the CI interconnection points for information exchange. The proposed solution is being applied to the Security Mediation Gateway being developed in the scope of the European FP7 MICIE project, to allow information exchange among interconnected CIs.
- Real-time simulation of cumulus clouds through SkewT/LogP diagramsPublication . P. Duarte, Rui; Gomes, Abel J.P.Modeling, simulation, and realistic rendering of natural phenomena have been important goals in computer graphics for decades. Clouds, as a natural phenomenon, represent a real challenge because their birth, life, and death are amorphous and dynamic in nature. As a consequence, cloud simulation is very time-consuming when using physically-based methods. This paper presents a real-time cloud simulation method based on SkewT/LogP diagrams to overcome this time performance problem. These diagrams allow us to simulate 3D clouds from sounding data made public worldwide by weather agencies. More specifically, a SkewT/LogP diagram describes the vertical motion of a cloud in the atmosphere, i.e., our cloud simulator system is based on physics but avoids solving differential equations of cloud motion to achieve real-time rates. We have also built a visual tool for 2D SkewT/LogP diagrams that allows us to inspect, control and simulate the thermodynamic process of ascending clouds in the atmosphere, as well as a 3D synthetic environment where clouds are advected by buoyant forces. This lightweight physicallybased technique enables the incorporation of our cloud simulator in systems tied to important industries, namely movies, virtual environments, and video games.
- Participation SpherePublication . Quental, Carlos; Gouveia, Luis BorgesThe e-participation can be considered an area under constant focus. In the context of Portuguese teacher unions, the adoption of information and communication technologies is nowadays a reality. However, their internet portals are mostly concentrated on unidirectional information dissemination between union representatives and other education stakeholders, and more. Interaction, participation, and collaboration is needed. In this regard, the use of e-participation platforms is expected to strengthen the relationship between trade unions and the education community. This paper presents a brief analysis of e-participation and e-democracy, proposes a conceptual communication model for digital mediation on teachers’ trade unions, a proof of concept – the Liberopinion platform - and addresses an initiative carried out by the most representative teacher’s union of Portugal, the National Federation of Teachers. This proposal is based on social media principles, designed to gather teachers and unions in a shared deliberative space and intend to encourage them to participate in educational debates. The Liberopinion platform enables effective participation in formal and informal decision-making processes via the Internet, either as standalone or widgets with full integration into any Website. It is under constant development and has been improved to support Participatory budgeting. It is currently being used in the Participatory Budget of Portugal. The actors in this study were chosen from the National Federation of Teachers due to its representativeness regarding associate teachers and provide an opportunity to assess the platform potential to support participation in a union context.
- Improving bluetooth beacon-based indoor location and fingerprintingPublication . Martins, Pedro; Abbasi, Maryam; Sá, Filipe; Cecílio, José; Morgado, Francisco; Caldeira, FilipeThe complex way radio waves propagate indoors, leads to the derivation of location using fngerprinting techniques. In this cases, location is computed relying on WiFi signals strength mapping. Recent Bluetooth low energy (BLE) provides new opportunities to explore positioning. In this work is studied how BLE beacons radio signals can be used for indoor location scenarios, as well as their precision. Additionally, this paper also introduces a method for beacon-based positioning, based on signal strength measurements at key distances for each beacon. This method allows to use diferent beacon types, brands, and location conditions/constraints. Depending on each situation (i.e., hardware and location) it is possible to adapt the distance measuring curve to minimize errors and support higher distances, while at the same time keeping good precision. Moreover, this paper also presents a comparison with traditional positioning method, using formulas for distance estimation, and the position triangulation. The proposed study is performed inside the campus of Viseu Polytechnic Institute, and tested using a group of students, each with his smart-phone, as proof of concept. Experimental results show that BLE allows having < 1.5 m error approximately 90% of the times, and the experimental results using the proposed location detection method show that the proposed position technique has 13.2% better precision than triangulation, for distances up to 10 m.
- Combining K-Means and XGBoost Models for Anomaly Detection Using Log DatasetsPublication . Henriques, João; Caldeira, Filipe; Cruz, Tiago; Simões, PauloAbstract: Computing and networking systems traditionally record their activity in log files, which have been used for multiple purposes, such as troubleshooting, accounting, post-incident analysis of security breaches, capacity planning and anomaly detection. In earlier systems those log files were processed manually by system administrators, or with the support of basic applications for filtering, compiling and pre-processing the logs for specific purposes. However, as the volume of these log files continues to grow (more logs per system, more systems per domain), it is becoming increasingly difficult to process those logs using traditional tools, especially for less straightforward purposes such as anomaly detection. On the other hand, as systems continue to become more complex, the potential of using large datasets built of logs from heterogeneous sources for detecting anomalies without prior domain knowledge becomes higher. Anomaly detection tools for such scenarios face two challenges. First, devising appropriate data analysis solutions for effectively detecting anomalies from large data sources, possibly without prior domain knowledge. Second, adopting data processing platforms able to cope with the large datasets and complex data analysis algorithms required for such purposes. In this paper we address those challenges by proposing an integrated scalable framework that aims at efficiently detecting anomalous events on large amounts of unlabeled data logs. Detection is supported by clustering and classification methods that take advantage of parallel computing environments. We validate our approach using the the well known NASA Hypertext Transfer Protocol (HTTP) logs datasets. Fourteen features were extracted in order to train a k-means model for separating anomalous and normal events in highly coherent clusters. A second model, making use of the XGBoost system implementing a gradient tree boosting algorithm, uses the previous binary clustered data for producing a set of simple interpretable rules. These rules represent the rationale for generalizing its application over a massive number of unseen events in a distributed computing environment. The classified anomaly events produced by our framework can be used, for instance, as candidates for further forensic and compliance auditing analysis in security management.
- Intrusion and anomaly detection for the next-generation of industrial automation and control systemsPublication . Rosa, Luis; Cruz, Tiago; Freitas, Miguel Borges de; Quitério, Pedro; Henriques, João; Caldeira, Filipe; Monteiro, Edmundo; Simões, PauloThe next-generation of Industrial Automation and Control Systems (IACS) and Supervisory Control and Data Acquisition (SCADA) systems pose numerous challenges in terms of cybersecurity monitoring. We have been witnessing the convergence of OT/IT networks, combined with massively distributed metering and control scenarios such as smart grids. Larger and geographically widespread attack surfaces, and inherently more data to analyse, will become the norm. Despite several advances in recent years, domain-specific security tools have been facing the challenges of trying to catch up with all the existing security flaws from the past, while also accounting for the specific needs of the next-generation of IACS. Moreover, the aggregation of multiple techniques and sources of information into a comprehensive approach has not been explored in depth. Such a holistic perspective is paramount since it enables a global and enhanced analysis enabled by the usage, combination and aggregation of the outputs from multiple sources and techniques. This paper starts by providing a review of the more recent anomaly detection techniques for SCADA systems, focused on both theoretical machine learning approaches and complete frameworks. Afterwards, it proposes a complete framework for an Intrusion and Anomaly Detection System (IADS) composed of specific detection probes, an event processing layer and a core anomaly detection component, amongst others. Finally, the paper presents an evaluation of the framework within a large-scale hybrid testbed, and a comparison of different anomaly detection scenarios based on various machine learning techniques.
- A Model for Planning TELCO Work-Field Activities Enabled by Genetic and Ant Colony AlgorithmsPublication . Henriques, J.; Caldeira, FilipeTelecommunication Company’s (TELCO) are continuously delivering their efforts on the effectiveness of their daily work. Planning the activities for their workers is a crucial sensitive, and time-consuming task usually taken by experts. This plan aims to find an optimized solution maximizing the number of activities assigned to workers and minimizing the inherent costs (e.g., labor from workers, fuel, and other transportation costs). This paper proposes a model that allows computing a maximized plan for the activities assigned to their workers, allowing to alleviate the burden of the existing experts, even if supported by software implementing rule-based heuristic models. The proposed model is inspired by nature and relies on two stages supported by Genetic and Ant Colony evolutionary algorithms. At the first stage, a Genetic Algorithms (GA) identifies the optimal set of activities to be assigned to workers as the way to maximize the revenues. At a second step, an Ant Colony algorithm searches for an efficient path among the activities to minimize the costs. The conducted experimental work validates the effectiveness of the proposed model in the optimization of the planning TELCO work-field activities in comparison to a rule-based heuristic model.
- Multi-Device Nutrition ControlPublication . Cunha, Carlos A. S.; P. Duarte, RuiPrecision nutrition is a popular eHealth topic among several groups, such as athletes, 1 people with dementia, rare diseases, diabetes, and overweight. Its implementation demands tight 2 nutrition control, starting with nutritionists who build up food plans for specific groups or individuals. 3 Each person then follows the food plan by preparing meals and logging all food and water intake. 4 However, the discipline demanded to follow food plans and log food intake turns out into high 5 dropout rates. This article presents the concepts, requirements, and architecture of a solution that 6 assists the nutritionist in building up and revising food plans and the user following them. It does 7 so by minimizing human-computer interaction by integrating the nutritionist and user systems 8 and introducing off-the-shelf IoT devices in the system, such as temperature sensors, smartwatches, 9 smartphones, and smart bottles. An interaction time analysis using the Keystroke Level Model 10 provides a baseline for comparison in future work addressing both the use of machine learning and 11 IoT devices to reduce the interaction effort of users.
- Low-Cost Embedded System for Customer LoyaltyPublication . Lima, Mauro; Morgado, José F.; P. Duarte, RuiNowadays, digital marketing has become an indispensable tool for companies to promote and sell high quality products to cope with increasingly competitive markets. For these to be shaped according to the customer’s interests and preferences, technology has been pushed to evolve every day trying to keep up with a high global demand. However, there is a particular problem in identifying and locating people in indoors spaces. Many applications were developed leveraging beacon’s technology that range from user’s localization and indoor navigation to personalized assistants that would assist in the decision making process. This, however, is still an open problem due to the difficulty in creating scalable indoor navigation systems, that are independent of the physical plan, and lack of precision in the detection of the customer indoor position. This paper will disclose the possibility to develop an efficient, low-cost indoor navigation system that solves both problems. It proposes an improvement on the accuracy of customer-beacon proximity distance, and a plan-free navigation method is proposed which allows customers to travel from a position to a specific beacon. Moreover, we integrate this with the concept of proximity marketing to embed the system in a physical context, focused on product promotions to increase customer loyalty.