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Publicações

2017

Teaching/Learning PBL Activity: Gantry Crane Control System Implementation

Autores
Correia, A; Amaro, B; Junior, E; Barbosa, J; Pinto, T; Bicho, E; Soares, F; Oliveira, PM;

Publicação
2017 25TH MEDITERRANEAN CONFERENCE ON CONTROL AND AUTOMATION (MED)

Abstract
This paper presents a teaching/learning experiment running in the laboratorial curricular unit Project I of the 4th year of the Integrated Master in Industrial Electronics and Computers Engineering at the University of Minho. Project specifications were defined by the three teachers involved in the experience and students were encouraged to look on different solutions for a real-word problem. In a concurrent way, students designed, developed and implemented didactic rigs to control a gantry crane system. The control was performed in open-loop, based on the Posicast feedforward technique, and in closed-loop, using a two-degrees of freedom configuration. The experiment procedure and the project outcomes of two solutions proposed by the students are presented.

2017

Combining Ranking with Traditional Methods for Ordinal Class Imbalance

Autores
Cruz, R; Fernandes, K; Costa, JFP; Ortiz, MP; Cardoso, JS;

Publicação
ADVANCES IN COMPUTATIONAL INTELLIGENCE, IWANN 2017, PT II

Abstract
In classification problems, a dataset is said to be imbalanced when the distribution of the target variable is very unequal. Classes contribute unequally to the decision boundary, and special metrics are used to evaluate these datasets. In previous work, we presented pairwise ranking as a method for binary imbalanced classification, and extended to the ordinal case using weights. In this work, we extend ordinal classification using traditional balancing methods. A comparison is made against traditional and ordinal SVMs, in which the ranking adaption proposed is found to be competitive.

2017

SafeFS: a modular architecture for secure user-space file systems: one FUSE to rule them all

Autores
Pontes, Rogerio; Burihabwa, Dorian; Maia, Francisco; Paulo, Joao; Schiavoni, Valerio; Felber, Pascal; Mercier, Hugues; Oliveira, Rui;

Publicação
Proceedings of the 10th ACM International Systems and Storage Conference, SYSTOR 2017, Haifa, Israel, May 22-24, 2017

Abstract
The exponential growth of data produced, the ever faster and ubiquitous connectivity, and the collaborative processing tools lead to a clear shift of data stores from local servers to the cloud. This migration occurring across different application domains and types of users|individual or corporate|raises two immediate challenges. First, outsourcing data introduces security risks, hence protection mechanisms must be put in place to provide guarantees such as privacy, confidentiality and integrity. Second, there is no \one-size-fits-all" solution that would provide the right level of safety or performance for all applications and users, and it is therefore necessary to provide mechanisms that can be tailored to the various deployment scenarios. In this paper, we address both challenges by introducing SafeFS, a modular architecture based on software-defined storage principles featuring stackable building blocks that can be combined to construct a secure distributed file system. SafeFS allows users to specialize their data store to their specific needs by choosing the combination of blocks that provide the best safety and performance tradeoffs. The file system is implemented in user space using FUSE and can access remote data stores. The provided building blocks notably include mechanisms based on encryption, replication, and coding. We implemented SafeFS and performed indepth evaluation across a range of workloads. Results reveal that while each layer has a cost, one can build safe yet efficient storage architectures. Furthermore, the different combinations of blocks sometimes yield surprising tradeoffs. © 2017 ACM.

2017

AUTOMATIC MUSICAL KEY ESTIMATION WITH ADAPTIVE MODE BIAS

Autores
Bernardes, G; Davies, MEP; Guedes, C;

Publicação
2017 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH AND SIGNAL PROCESSING (ICASSP)

Abstract
In this paper we present the INESC Key Detection (IKD) system which incorporates a novel method for dynamically biasing key mode estimation using the spatial displacement of beat-synchronous Tonal Interval Vectors (TIVs). We evaluate the performance of the IKD system at finding the global key on three annotated audio datasets and using three key-defining profiles. Results demonstrate the effectiveness of the mode bias in favoring either the major or minor mode, thus allowing users to fine tune this variable to improve correct key estimates on style-specific music datasets or to balance predictions across key modes on unknown input sources.

2017

Fabry-Perot cavity based on air bubble for high sensitivity lateral load and strain measurements

Autores
Novais, S; Ferreira, MS; Pinto, JL;

Publicação
THIRD INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
A Fabry-Perot air bubble microcavity fabricated between a section of single mode fiber and a multimode fiber is proposed. The study of the microcavities growth with the number of applied arcs is performed. The sensors are tested for lateral load and strain, where sensitivities of 0.32 nm/N and 2.11 nm/N and of 4.49 pm/mu epsilon and 9.12 pm/mu epsilon are obtained for the 47 mu m and 161 mu m long cavities, respectively. The way of manufacturing using a standard fusion splicer and given that no oils or etching solutions are involved, emerges as an alternative to the previously developed air bubble based sensors.

2017

The Semantics of Movie Metadata: Enhancing User Profiling for Hybrid Recommendation

Autores
Soares, M; Viana, P;

Publicação
RECENT ADVANCES IN INFORMATION SYSTEMS AND TECHNOLOGIES, VOL 1

Abstract
In movie/TV collaborative recommendation approaches, ratings users gave to already visited content are often used as the only input to build profiles. However, users might have rated equally the same movie but due to different reasons: either because of its genre, the crew or the director. In such cases, this rating is insufficient to represent in detail users' preferences and it is wrong to conclude that they share similar tastes. The work presented in this paper tries to solve this ambiguity by exploiting hidden semantics in metadata elements. The influence of each of the standard description elements (actors, directors and genre) in representing user's preferences is analyzed. Simulations were conducted using Movielens and Netflix datasets and different evaluation metrics were considered. The results demonstrate that the implemented approach yields significant advantages both in terms of improving performance, as well as in dealing with common limitations of standard collaborative algorithm.

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