Cookies Policy
The website need some cookies and similar means to function. If you permit us, we will use those means to collect data on your visits for aggregated statistics to improve our service. Find out More
Accept Reject
  • Menu
About

About

Alexandre Valle de Carvalho has been a University Professor since 2001, and Assistant Professor in the Department of Computer Engineering (DEI) at the Faculty of Engineering of the University of Porto (FEUP) since 2009. He is a researcher at the Center for Information Systems and Computer Graphics (CSIG) at INESCTEC, since 2001 and senior researcher since 2009. The scientific area of Computer Graphics has been present throughout its academic path, starting with Raytracing and Radiosity Hybrid for the Calculation of Photorealistic Images, of 1994, in the Graphical Interface of the Input Module of Data from the VALORAGUA Model, from 1997, in the Image Synthesis for Virtual Environments Experiences with the RENDERCACHE technique, from 2001., culminating with his PhD entitled “Spatio-temporal Information Management and Visualization” in 2009. Furthermore, other professional activity in Geographic Information Systems, as a scholarship, technical staff and then as a researcher at INESC Porto, motivated the scientific study in this area and in the application domain of urban information management, eDemocracy and eGovernment. The joining of both areas - computer graphics and information systems - as well as the background in urban data management resulted in the theme and PhD work, in management and visualization of space-time information, completed in 2009, where he defended two hypothesis: one in information systems and another in information visualization. Alexandre performs research in these two areas until the present time. Furthermore, he has participated in a considerable number of research and development projects, framed by European projects, R&D national projects and specialized consultancy, having publications indexed in scientific conferences and journals. Regarding economic and direct knowledge extension to society, Alexandre founded SIAGHOS in 2012, towards systems and technology to support observational clinical studies. In this context, it conceived, produced and innovated in information systems to support the registration and analysis processes of observational clinical studies for hematology-oncology diseases. These systems were used by a considerable number of Portuguese hematologists, between 2012 and 2018. Furthermore, in 2015 Alexandre co-founded MITMYNID, an INESC TEC spinoff towards innovative solutions for the Transport and Logistics Sector. At MITMYNID, Alexandre participated in the coordination BIZCARGO and of projects with a high degree of innovation and in the elaboration and execution of proposals and provision of services where innovation is also evident. Examples of this are two P2020 demonstration projects and collaboration on two European projects. In the context of university management, Alexandre performed scientific and pedagogical coordination of curricular units, course groups and degree and master courses.

Interest
Topics
Details

Details

  • Name

    Alexandre Carvalho
  • Role

    Senior Researcher
  • Since

    09th March 1998
006
Publications

2023

BEYOND FRONT AND BACK OFFICE: VISUALIZATIONS, REPRESENTATIONS AND ACCESS THROUGH POSTCOLONIAL LENSES BETWEEN A RESEARCH PLATFORM AND AN ARTS EDUCATION ARCHIVE

Authors
Assis, T; Martins, C; Valle, A; Santos, A; Castro, J; Osório, L; Silva, P;

Publication
ICERI2023 Proceedings - ICERI Proceedings

Abstract

2023

A Comparison of Point Set Registration Algorithms for Quantification of Change in Spatiotemporal Data

Authors
Gomes M.; De Carvalho A.V.; Oliveira M.A.; Carneiro E.;

Publication
Iberian Conference on Information Systems and Technologies, CISTI

Abstract
Point Set Registration (PSR) algorithms have very different underlying theoretical models to define a process that calculates the alignment solution between two point clouds. The selection of a particular PSR algorithm can be based on the efficiency (time to compute the alignment) and accuracy (a measure of error using the estimated alignment). In our specific context, previous work used a CPD algorithm to detect and quantify change in spatiotemporal datasets composed of moving and shape-changing objects represented by a sequence of time stamped 2D polygon boundaries. Though the results were promising, we question if the selection of a particular PSR algorithm influences the results of detection and quantification of change. In this work we review and compare several PSR algorithms, characterize test datasets and used metrics, and perform tests for the selected datasets. The results show pyCPD and cyCPD implementations of CPD to be good alternatives and that BCPD can have potential to be yet another alternative. The results also show that detection and quantification accuracy change for some of the tested PSR implementations.

2021

A Comparative Study on the Performance of the IB+ Tree and the I2B+ Tree

Authors
Carneiro, E; de Carvalho, AV; Oliveira, MA;

Publication
Journal of Information Systems Engineering and Management

Abstract
Index structures were often used to optimise fetch operations to external storage devices (secondary memory). Nowadays, this also holds for increasingly large amounts of data residing in main-memory (primary memory). Within this scope, this work focuses on index structures that efficiently insert, query and delete valid-time data from very large datasets. This work performs a comparative study on the performance of the Interval B+ tree (IB+ tree) and the Improved Interval B+ tree (I2B+ tree): a variant that improves the time-efficiency of the deletion operation by reducing the number of traversed nodes to access siblings. We performed an extensive analysis of the performance of two operations: insertions and deletions, on both index structures, using multiple datasets with growing volumes of data, distinct temporal distributions and tree parameters (time-split alpha and node order). Results confirm that the I2B+ tree globally outperforms the IB+ tree, since, on average, deletion operations are 7% faster, despite insertions requiring 2% more time. Furthermore, results also allowed to determine the key factors that augment the performance difference on deletions between both trees. Copyright © 2021 by Author/s and Licensed by Veritas Publications Ltd., UK.

2021

Computer Graphics teaching challenges: Guidelines for balancing depth, complexity and mentoring in a confinement context

Authors
Rodrigues, R; Matos, T; de Carvalho, AV; Barbosa, JG; Assaf, R; Nóbrega, R; Coelho, A; de Sousa, AA;

Publication
Graph. Vis. Comput.

Abstract

2020

I2B+tree: Interval B plus tree variant towards fast indexing of time-dependent data

Authors
Carneiro, E; de Carvalho, AV; Oliveira, MA;

Publication
2020 15TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI'2020)

Abstract
Index structures are fast-access methods. In the past, they were often used to minimise fetch operations to external storage devices (secondary memory). Nowadays, this also holds for increasingly large amounts of data residing in main-memory (primary memory). Examples of software that deals with this fact are in-memory databases and mobile device applications. Within this scope, this paper focuses on index structures to store, access and delete interval-based time-dependent (temporal) data from very large datasets, in the most efficient way. Index structures for this domain have specific characteristics, given the nature of time and the requirement to index time intervals. This work presents an open-source time-efficiency focused variant of the original Interval B+ tree. We designate this variant Improved Interval B+ tree (I2B+ tree). Our contribution adds to the performance of the delete operation by reducing the amount of traversed nodes to access siblings. We performed an extensive analysis of insert, range queries and deletion operations, using multiple datasets with growing volumes of data, distinct temporal distributions and tree parameters (time-split and node order). Results of the experiments validate the logarithmic performance of these operations and propose the best-observed tree parameter ranges.

Supervised
thesis

2022

Model-Agnostic Generation Of Example-Based Explanations For The Post-Hoc Assessment Of Cervical Cytology Models

Author
Luís Henrique Condado Marques

Institution
UP-FEUP

2020

Gamified Interfaces as a means to motivate exploration and comprehension of Musical Genres

Author
Miguel Feliciano da Cunha Oliveira Duarte

Institution
UP-FEUP

2019

Face Detection and Recognition in Unconstrained Scenarios

Author
Anabela Machado Reigoto

Institution
UP-FEUP

2019

visualização de estatísticas pessoais e sociais para um produto web e mobile

Author
João Dias Barbosa

Institution
UP-FEUP

2019

Visualização de dados oceanográficos espácio-temporais multivariáveis em dispositivos móveis

Author
Rui Filipe Correia Gomes

Institution
UP-FEUP