São Paulo Federal Institute of Education, Science and Technology

About: São Paulo Federal Institute of Education, Science and Technology is a education organization based out in São Paulo, Brazil. It is known for research contribution in the topics: Context (language use) & Computer science. The organization has 1707 authors who have published 2374 publications receiving 11333 citations.

The impact of spatial data redundancy on SOLAP query performance

Abstract: Geographic Data Warehouses (GDW) are one of the main technologies used in decision-making processes and spatial analysis, and the literature proposes several conceptual and logical data models for GDW. However, little effort has been focused on studying how spatial data redundancy affects SOLAP (Spatial On-Line Analytical Processing) query performance over GDW. In this paper, we investigate this issue. Firstly, we compare redundant and non-redundant GDW schemas and conclude that redundancy is related to high performance losses. We also analyze the issue of indexing, aiming at improving SOLAP query performance on a redundant GDW. Comparisons of the SB-index approach, the star-join aided by R-tree and the star-join aided by GiST indicate that the SB-index significantly improves the elapsed time in query processing from 25% up to 99% with regard to SOLAP queries defined over the spatial predicates of intersection, enclosure and containment and applied to roll-up and drill-down operations. We also investigate the impact of the increase in data volume on the performance. The increase did not impair the performance of the SB-index, which highly improved the elapsed time in query processing. Performance tests also show that the SB-index is far more compact than the star-join, requiring only a small fraction of at most 0.20% of the volume. Moreover, we propose a specific enhancement of the SB-index to deal with spatial data redundancy. This enhancement improved performance from 80 to 91% for redundant GDW schemas.

Unleashing Tabular Content to Open Data: A Survey on PDF Table Extraction Methods and Tools

Abstract: Portable Document Format (PDF) has been a popular way to exchange data in documents since Adobe introduced the format in 1993. Its report-like characteristic which preserves and prioritizes graphical visualization was part of the main publishing concerns among several segments including government agencies. In this way, tabular data started to be enclosed within PDF documents and disclosed in government portals. This situation, apart being surprisingly contradictory to data openness, is still found even in the major open data initiatives. It is estimated that roughly 13% of published files in some main open data portals around the world have their data made available in PDF. Thus, there is a need for effective tools capable of extracting tabular content (a main placeholder for data) from PDF to allow its data to be published in more open formats such as the well-known CSV which complies with accessible and machine processable open data principles.This paper aims at providing a structured and comprehensive overview of the research in tabular content extraction specifically from PDF documents as well as to provide an overview of most recent practical results in the literature. The contribution of this work goes beyond theoretical discussions by helping data practitioners to understand to what extent methods and tools regarding tabular content extraction from PDF can benefit the open data initiatives in practical and effective ways.

Third Party Certification of Agri-Food Supply Chain Using Smart Contracts and Blockchain Tokens.

Abstract: Every consumer’s buying decision at the supermarket influences food brands to make first party claims of sustainability and socially responsible farming methods on their agro-product labels. Fine wines are often subject to counterfeit along the supply chain to the consumer. This paper presents a method for efficient unrestricted publicity to third party certification (TPC) of plant agricultural products, starting at harvest, using smart contracts and blockchain tokens. The method is capable of providing economic incentives to the actors along the supply chain. A proof-of-concept using a modified Ethereum IGR token set of smart contracts using the ERC-1155 standard NFTs was deployed on the Rinkeby test net and evaluated. The main findings include (a) allowing immediate access to TPC by the public for any desired authority by using token smart contracts. (b) Food safety can be enhanced through TPC visible to consumers through mobile application and blockchain technology, thus reducing counterfeiting and green washing. (c) The framework is structured and maintained because participants obtain economic incentives thus leveraging it´s practical usage. In summary, this implementation of TPC broadcasting through tokens can improve transparency and sustainable conscientious consumer behaviour, thus enabling a more trustworthy supply chain transparency.

An Adaptive Power Sharing Control for Management of DC Microgrids Powered by Fuel Cell and Storage System

Abstract: This paper presents an adaptive power-sharing methodology for management of dc microgrids powered by fuel cell (FC) and storage system (SS). In this context, the use of an adaptive k -sharing function in the control scheme is proposed to compensate the fast transients on the ac side and manage the power sharing at steady-state regime between the FC and SS. The adaptive k -sharing is implemented with a low-pass filter transfer function for the FC and a complementary transfer function associated with the adaptive k -sharing gain for the SS. The proposed adaptive k -sharing function links the FC and the SS dynamics with the management of the dc microgrid, ensuring that the entire FC operation is performed in accordance with its operational limits. One of the main advantages of the proposed adaptive k -sharing is to reach high levels of stability and minimum disruptions on the FC terminals. To evaluate the feasibility of the proposed approach, we analyze the k -sharing behavior to determine the operational limits of the dc microgrid. Finally, to support the theoretical analysis, we carried out a set of experimental results.