2018
Authors
Leite, R; Rocha, R;
Publication
VECPAR
Abstract
This paper presents LRMalloc, a lock-free memory allocator that leverages lessons of modern memory allocators and combines them with a lock-free scheme. Current state-of-the-art memory allocators possess good performance but lack desirable lock-free properties, such as, priority inversion tolerance, kill-tolerance availability, and/or deadlock and livelock immunity. LRMalloc’s purpose is to show the feasibility of lock-free memory management algorithms, without sacrificing competitiveness in comparison to commonly used state-of-the-art memory allocators, especially for concurrent multithreaded applications.
2018
Authors
Areias, M; Rocha, R;
Publication
THEORY AND PRACTICE OF LOGIC PROGRAMMING
Abstract
One of the main advantages of Prolog is its potential for the implicit exploitation of parallelism and, as a high-level language, Prolog is also often used as a means to explicitly control concurrent tasks. Tabling is a powerful implementation technique that overcomes some limitations of traditional Prolog systems in dealing with recursion and redundant subcomputations. Given these advantages, the question that arises is if tabling has also the potential for the exploitation of concurrency/parallelism. On one hand, tabling still exploits a search space as traditional Prolog but, on the other hand, the concurrent model of tabling is necessarily far more complex, since it also introduces concurrency on the access to the tables. In this paper, we summarize Yap's main contributions to concurrent tabled evaluation and we describe the design and implementation challenges of several alternative table space designs for implicit and explicit concurrent tabled evaluation that represent different tradeoffs between concurrency and memory usage. We also motivate for the advantages of using fixed-size and lock freedata structures, elaborate on the key role that the engine's memory allocator plays on such environments, and discuss how Yap's mode-directed tabling support can be extended to concurrent evaluation. Finally, we present our future perspectives toward an efficient and novel concurrent framework which integrates both implicit and explicit concurrent tabled evaluation in a single Prolog engine.
2018
Authors
Cósta, J; Silva, C; Antunes, M; Ribeiro, B;
Publication
IJCNN
Abstract
Current challenges in machine learning include dealing with temporal data streams, drift and non-stationary scenarios, often with text data, whether in social networks or in business systems. This dynamic nature tends to limit the performance of traditional static learning models and dynamic learning strategies must be put forward. However, acquiring the performance of those strategies is not a straightforward issue, as sample's dependency undermines the use of validation techniques, like crossvalidation. In this paper we propose to use the McNemar's test to compare two distinct approaches that tackle adaptive learning in dynamic environments, namely DARK (Drift Adaptive Retain Knowledge) and Learn++. NSE (Learn++ for Non-Stationary Environments). The validation is based on a Twitter case study benchmark constructed using the DOTS (Drift Oriented Tool System) dataset generator. The results obtained demonstrate the usefulness and adequacy of using McNemar's statistical test in dynamic environments where time is crucial for the learning algorithm. © 2018 IEEE.
2018
Authors
Carnaz, G; Nogueira, VB; Antunes, M; Fonseca Ferreira, NM;
Publication
SoCPaR
Abstract
Information Extraction (IE) and fusion are complex fields and have been useful in several domains to deal with heterogeneous data sources. Criminal police are challenged in forensics activities with the extraction, processing and interpretation of numerous documents from different types and with distinct formats (templates), such as narrative criminal reports, police databases and the result of OSINT activities, just to mention a few. Such challenges suggest, among others, to cope with and manually connect some hard to interpret meanings, such as license plates, addresses, names, slang and figures of speech. This paper aims to deal with forensic IE and fusion, thus a system was proposed to automatically extract, transform, clean, load and connect police reports that arrived from different sources. The same system aims to help police investigators to identify and correlate interesting extracted entities.
2018
Authors
Antunes, M; Rabadão, C;
Publication
Proceedings of the Tenth International Conference on Soft Computing and Pattern Recognition, SoCPaR 2018, Porto, Portugal, December 13-15, 2018
Abstract
Individuals and companies have a feeling of insecurity in the Internet, as every day a reasonable amount of attacks take place against users’ privacy and confidentiality. The use of digital equipment in illicit and unlawful activities has increasing. Attorneys, criminal polices, layers and courts staff have to deal with crimes committed with digital “weapons”, whose evidences have to be examined and reported by applying digital forensics methods. Digital forensics is a recent and fast-growing area of study which needs more graduated professionals. This fact has leveraged higher education institutions to develop courses and curricula to accommodate digital forensics topics and skills in their curricular offers. This paper aims to present the development of a cybersecurity and digital forensics master course in Polytechnic of Leiria, a public higher education institution in Portugal. The authors depict the roadmap and the general milestones that lead to the development of the course. The strengths and opportunities are identified and the major students’ outcomes are pointed out. The way taken and the decisions made are also approached, with a view to understanding the performance obtained so far. © 2020, Springer Nature Switzerland AG.
2018
Authors
Harrison, C; Keles, S; Hudson, R; Shin, S; Dutra, I;
Publication
IPDPS Workshops
Abstract
We explore the feasibility of a database storage engine housing up to 307 billion genetic Single Nucleotide Polymorphisms (SNP) for online access. We evaluate database storage engines and implement a solution utilizing factors such as dataset size, information gain, cost and hardware constraints. Our solution provides a full feature functional model for scalable storage and query-ability for researchers exploring the SNP's in the human genome. We address the scalability problem by building physical infrastructure and comparing final costs to a major cloud provider.
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