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Details

  • Name

    Alexandre Carvalho
  • Cluster

    Computer Science
  • Role

    Senior Researcher
  • Since

    09th March 1998
Publications

2016

Spatial-Temporal Data Watch to Digital Media PhD Thesis Proposal in Informatics Engineering

Authors
Dias, L; Carvalho, A; Coelho, A;

Publication
2016 11TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI)

Abstract
This paper presents a PhD thesis proposal in Informatics Engineering, scheduled for completion in July 2018. This PhD thesis is part of Spatio-Temporal Information Systems, with applicability in technological communication tools and visual representation of knowledge, for Digital Media (newspapers, radio and television). It is intended to maximize the efficiency and effectiveness of the value of heterogeneous, multivariate, multidimensional information characteristic of this context, produced and shared by different sources, in different formats. It is hoped that participation in this Doctoral Symposium will enrich and update the work in progress and help the preparation of the PhD thesis proposal.

2016

Monitoring Systems for Parallel Distributed Data Management Systems

Authors
Pinho, E; de Carvalho, AV;

Publication
2016 11TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI)

Abstract
Usually, a Big Data system has a monitoring system for performance evaluation and error prevention. Although, there are some disadvantages in the way that these tools display the information and its targeted approach to physical components. The main goal is to study visual and interaction mechanisms that allow the representation of monitoring data in grid computing environments, providing the end-user information which can contribute objectively to the system analysis. This paper has the purpose to present the state of the art, carries out an intermediate evaluation of the current work and present the proposed solution.

2015

Improving Geolocation by Combining GPS with Image Analysis

Authors
Pinho, F; Carvalho, A; Carreira, R;

Publication
GEOINFORMATICS FOR INTELLIGENT TRANSPORTATION

Abstract
The Global Positioning System (GPS) provides geolocation to a considerable number of applications in domains such as agriculture, commerce, transportation and tourism. Operational factors such as signal noise or the lack of direct vision from the receiver to the satellites, reduce the GPS geolocation accuracy. Urban canyons are a good example of an environment where continuous GPS signal reception may fail. For some applications, the lack of geolocation accuracy, even if happening for a short period of time, may lead to undesired results. For instance, consider the damages caused by the failure of the geolocation system in a city tour-bus transportation that shows location-sensitive data (historical/cultural data, publicity) in its screens as it passes by a location. This work presents an innovative approach for keeping geolocation accurate in mobile systems that rely mostly on GPS, by using computer vision to help providing geolocation data when the GPS signal becomes temporarily low or even unavailable. Captured frames of the landscape surrounding the mobile system are analysed in real-time by a computer vision algorithm, trying to match it with a set of geo-referenced images in a preconfigured database. When a match is found, it is assumed that the mobile system current location is close to the GPS location of the corresponding matched point. We tested this approach several times, in a real world scenario, and the results achieved evidence that geolocation can effectively be improved for scenarios where GPS signal stops being available.

2013

Retrieval of Very Large Temporal Datasets for Interactive Tasks

Authors
de Carvalho, AV; Oliveira, MA; Rocha, A;

Publication
PROCEEDINGS OF THE 2013 8TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI 2013)

Abstract
Many tasks dealing with temporal data, such as interactive browse through temporal datasets, require intensive retrieval from the database. Depending on the user's task, the data retrieved may be too large to fit in the local memory. Even if it fits, the time taken to retrieve the data may compromise user interaction. This work proposes a method, TravelLight, which improves interactive traveling across very large temporal datasets by exploring the temporal consistency of data items. The proposed method consists of two algorithms: the data retrieval and the memory management algorithm, both contributing to improve memory usage and, most important, to reduce the turnaround time. Results are reported concerning experiments with a temporally linear navigation across two datasets of one million items, which differ in the average time span of items. With the obtained results it is possible to conclude that the proposed method reduces turnaround time thus enhancing the response of interactive tasks over very large temporal datasets.

2006

Proposta para um Web Feature Service Temporal

Authors
Artur Jorge da Silva Rocha; Alexandre Carvalho

Publication
Actas da XATA'2006 - XATA'2006 XML - Aplicações e Tecnologias Associadas, pp.212-223, Portalegre, Portugal

Abstract

Supervised
thesis

2016

Monitoring systems for parallel distributed data management systems

Author
Emanuel Augusto Santos Pinho

Institution
UP-FEUP