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Publicações

2016

The self-configuration of nodes using RSSI in a dense wireless sensor network

Autores
Abdellatif, MM; Oliveira, JM; Ricardo, M;

Publicação
TELECOMMUNICATION SYSTEMS

Abstract
Wireless sensor networks (WSNs) may be made of a large amount of small devices that are able to sense changes in the environment, and communicate these changes throughout the network. An example of a similar network is a photo voltaic (PV) power plant, where there is a sensor connected to each solar panel. The task of each sensor is to sense the output of the panel which is then sent to a central node for processing. As the network grows, it becomes impractical and even impossible to configure all these nodes manually. And so, the use of self-organization and auto-configuration algorithms becomes essential. In this paper, three algorithms are proposed that allow nodes in the network to automatically identify their closest neighbors, relative location in the network, and select which frequency channel to operate in. This is done using the value of the Received Signal Strength Indicator (RSSI) of the messages sent and received during the setup phase. The performance of these algorithms is tested by means of both simulations and testbed experiments. Results show that the error in the performance of the algorithms decreases as we increase the number of RSSI values used for decision making. Additionally, the number of nodes in the network affects the setup error. However, the value of the error is still acceptable even with a high number of nodes.

2016

Analyzing Social Media Discourse An Approach using Semi-supervised Learning

Autores
Figueira, A; Oliveira, L;

Publicação
PROCEEDINGS OF THE 12TH INTERNATIONAL CONFERENCE ON WEB INFORMATION SYSTEMS AND TECHNOLOGIES, VOL 2 (WEBIST)

Abstract
The ability to handle large amounts of unstructured information, to optimize strategic business opportunities, and to identify fundamental lessons among competitors through benchmarking, are essential skills of every business sector. Currently, there are dozens of social media analytics' applications aiming at providing organizations with informed decision making tools. However, these applications rely on providing quantitative information, rather than qualitative information that is relevant and intelligible for managers. In order to address these aspects, we propose a semi-supervised learning procedure that discovers and compiles information taken from online social media, organizing it in a scheme that can be strategically relevant. We illustrate our procedure using a case study where we collected and analysed the social media discourse of 43 organizations operating on the Higher Public Polytechnic Education Sector. During the analysis we created an "editorial model" that characterizes the posts in the area. We describe in detail the training and the execution of an ensemble of classifying algorithms. In this study we focus on the techniques used to increase the accuracy and stability of the classifiers.

2016

Report on FSCD 2016: 1st International Conference on Formal Structures for Computation and Deduction

Autores
Alves, Sandra;

Publicação
SIGLOG News

Abstract

2016

Distinct immune response but similar innervation and molecular profiles in human hip osteoarthritis and implants aseptic loosening

Autores
Vasconcelos, DM; Silva, MR; Mateus, A; Alves, J; Machado, GC; Santos, JM; Carvalho, DP; Alencastre, IS; Henrique, R; Costa, G; Barbosa, MA; Lamghari, M;

Publicação
MEDICINE

Abstract

2016

Model-based predictive control implementation for cooperative adaptive cruise control

Autores
Lopes, A; Araújo, RE;

Publicação
U.Porto Journal of Engineering

Abstract
The automation of road vehicles has become a necessity to improve the efficiency and safety of this system. In a vehicle formation it is important to maintain a safety distance between the vehicles. The control of a vehicle spacing distance and longitudinal velocity can be achieved through the implementation of a model-based predictive controller. This implementation of a cooperative adaptive cruise control allows the access of another vehicle state information through vehicular communication technology and promote state prediction and ultimately system stability. The optimization algorithm performs the computation of the control input in a control horizon window and ensures that the spacing error takes only positive values. The results of the proposed controller are evaluated through the computational tool Simulink in the two-vehicle platoon. The controller is implemented in the precedent vehicle. To assess the performance of the proposed controller different control parameters and constraints were used.

2016

LV SCADA project: In-field validation of a distribution state estimation tool for LV networks

Autores
Barbeiro, P; Pereira, J; Teixeira, H; Seca, L; Silva, P; Silva, N; Melo, F;

Publicação
IET Conference Publications

Abstract
The LV SCADA project aimed at the development of advanced technical, commercial and regulatory solutions to contribute for an effective smart grid implementation. One of the biggest challenges of the project was related with the lack of characterization that usually exists in LV networks, together with the almost non-existing observability. In order to overcome these issues, a LV management system integrating a state estimation tool based on artificial intelligence techniques was developed. The tool is currently installed in one pilot demonstration site that aggregates 2 MV/LV substations. In this paper the performance of tool in real environment is evaluated and the results gathered from the pilot site are analyzed.

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