2013
Autores
Cunha, J; Fernandes, JP; Mendes, J; Pereira, R; Saraiva, J;
Publicação
2013 IEEE SYMPOSIUM ON VISUAL LANGUAGES AND HUMAN-CENTRIC COMPUTING (VL/HCC 2013)
Abstract
Spreadsheets are being used with many different purposes that range from toy applications to complete information systems. In any of these cases, they are often used as data repositories that can grow significantly. As the amount of data grows, it also becomes more difficult to extract concrete information out of them. This paper focuses on the problem of spreadsheet querying. In particular, we propose an expressive and composable technique where intuitive queries can be defined. Our approach builds on a model-driven spreadsheet development environment, and queries are expressed referencing entities in the model of a spreadsheet instead of in its actual data. Finally, the system that we have implemented relies on Google's query function for spreadsheets.
2013
Autores
Poínhos, Rui; Oliveira, Bruno; Correia, Flora;
Publicação
Abstract
[Abstract]
2013
Autores
Delgado, C; Castelo, BM;
Publicação
Encyclopedia of Corporate Social Responsibility
Abstract
[No abstract available]
2013
Autores
Teixeira, AAC; Soeiro, M;
Publicação
SINGAPORE ECONOMIC REVIEW
Abstract
We apply the contingent valuation method to estimate how much a specific group of society, which is relatively prone to falling victim to crime, is willing to pay to reduce the likelihood of being the victim of violent crime. Based on responses from 1122 students, we found that younger and female students revealed that they are more inclined to pay so as to avoid violent crime. Students' field of study, cautious behavior and a strong opinion about policies and payment vehicles with potential to reduce the risk of crime are key determinants of the willingness to pay.
2013
Autores
Neves, R; Madeira, A; Martins, MA; Barbosa, LS;
Publicação
IRI (best papers)
Abstract
Lightweight formal methods, of which Alloy is a prime example, combine the rigour of mathematics without compromising simplicity of use and suitable tool support. In some cases, however, the verification of safety or mission critical software entails the need formore sophisticated technologies, typically based on theorem provers. This explains a number of attempts to connect Alloy to specific theorem provers documented in the literature. This chapter, however, takes a different perspective: instead of focusing on one more combination of Alloy with still another prover, it lays out the foundations to fully integrate this system in the Hets platform which supports a huge network of logics, logic translators and provers. This makes possible for Alloy specifications to “borrow” the power of several, non dedicated proof systems. The chapter extends the authors’ previous work on this subject by developing in full detail the semantical foundations for this integration, including a formalisation of Alloy as an institution, and introducing a new, more general translation of the latter to second-order logic.
2013
Autores
Paulo, J; Reis, P; Pereira, J; Sousa, A;
Publicação
COMPUTER SYSTEMS SCIENCE AND ENGINEERING
Abstract
Deduplication has proven to be a valuable technique for eliminating duplicate data in backup and archival systems and is now being applied to new storage environments with distinct requirements and performance trade-offs. Namely, deduplication system are now targeting large-scale cloud computing storage infrastructures holding unprecedented data volumes with a significant share of duplicate content. It is however hard to assess the usefulness of deduplication in particular settings and what techniques provide the best results. In fact, existing disk I/O benchmarks follow simplistic approaches for generating data content leading to unrealistic amounts of duplicates that do not evaluate deduplication systems accurately. Moreover, deduplication systems are now targeting heterogeneous storage environments, with specific duplication ratios, that benchmarks must also simulate. We address these issues with DEDISbench, a novel micro-benchmark for evaluating disk I/O performance of block based deduplication systems. As the main contribution, DEDISbench generates content by following realistic duplicate content distributions extracted from real datasets. Then, as a second contribution, we analyze and extract the duplicates found on three real storage systems, proving that DEDISbench can easily simulate several workloads. The usefulness of DEDISbench is shown by comparing it with Bonnie++ and IOzone open-source disk I/O micro-benchmarks on assessing two open-source deduplication systems, Opendedup and Lessfs, using Ext4 as a baseline. Our results lead to novel insight on the performance of these file systems.
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