Formal verification of PLC programs using the B Method

PLCs (acronym for Programmable Logic Controllers) perform control operations, receiving information from the environment, processing it and modifying this same environment according to the results produced. They are commonly used in industry in several applications, from mass transport to petroleum industry. As the complexity of these applications increase, and as various are safety critical, a necessity for ensuring that they are reliable arouses. Testing and simulation are the de-facto methods used in the industry to do so, but they can leave flaws undiscovered. Formal methods can provide more confidence in an application s safety, once they permit their mathematical verification. We make use of the B Method, which has been successfully applied in the formal verification of industrial systems, is supported by several tools and can handle decomposition, refinement, and verification of correctness according to the specification. The method we developed and present in this work automatically generates B models from PLC programs and verify them in terms of safety constraints, manually derived from the system requirements. The scope of our method is the PLC programming languages presented in the IEC 61131-3 standard, although we are also able to verify programs not fully compliant with the standard. Our approach aims to ease the integration of formal methods in the industry through the abbreviation of the effort to perform formal verification in PLCs

Associativismo nos municípios rurais: uma alternativa de desenvolvimento local em Portalegre/RN

This work aims to study the associations as mediating the process of social change and its importance for local development. The hypothesis is that associations, but bring dynamism to the smaller cities and improve the living conditions of their members, relegated to the background social sustainability, understood this as a permanent exercise of mobilization and participation in community life. The assumptions of the study are that the practice group has influenced the processes of local development in Brazilian rural municipalities through the mediation of government programs and projects aimed at combating rural poverty require social organization for their achievement. The concept of local development in this work was rescued from studies of political economy and sociology. But the concepts of collective action and partnerships advêem studies of political participation and social development of the theory of alternative or solidarity. The party consisted of an empirical case study conducted with four associations of farmers in the municipality of Portalegre-RN. Why choose qualitative study was used the technique of semi-structured interviews with the chairmen I members of associations and other actors considered essential to understanding the study (religious leaders, local political power and chairman of the union of rural workers), a total of 20 interviews, in addition to the observations of field and documentary research in records of the.ir own organizations. The survey results show that the performance of groups of farmers are key components and determinants for the production I marketing of agricultural products and for boosting the economy, as well as security for minimum levels of citizenship. Yet we are still in a space purpose of social change, which comes to confirm the initial hypothesis of this work

Os programas de governo no horário gratuito de propaganda eleitoral:um estudo das eleições governamentais no Rio Grande do Norte em 2006

In Brazil, the Free Political advertising time (HGPE) represents one of the main venues for the contest between political parties, revealing a tool that streamlines the electoral dispute and enables all sectors and social classes of important information about dispute over candidates. In HGPE, political groups have the opportunity to present their programs of government and discuss issues that relate to the demands of the population. This research sought to examine the role played by so-called "government programs" in the electoral race for governor of Rio Grande do Norte in 2006, which had as main candidates, two traditional characters of the political landscape in Natal: Wilma de Faria (PSB) and Garibaldi Alves Filho (PMDB). According to our analysis, discussion of government programs such candidates in HGPE had not meant to enlighten the voters about the political projects designed, not just the desire to build an image of seriousness and competence of candidates, but appeared as a means to meet the schedule imposed by the opponent and as a strategic resource to select a specific segment of the electorate.

The trajectory of social housing policy in Brazil: From the National Housing Bank to the Ministry of the Cities

This paper discusses social housing policy in Brazil since the 1990s by analyzing government programs’ institutional arrangements, their sources of revenues and the formatting of related financial systems. The conclusion suggests that all these arrangements have not constituted a comprehensive housing policy with the clear aim of serving to enhance housing conditions in the country. Housing ‘policies’ since the 1990s – as proposed by Fernando Collor de Mello, Itamar Franco, Fernando Henrique Cardoso and ´ Luis Inacio Lula da Silva’s governments (in the latter case, despite much progress towards subsidized investment programs) – have sought to consolidate financial instruments in line with global markets, restructuring the way private interests operate within the system, a necessary however incomplete course of action. Different from rhetoric, this has resulted in failure as the more fundamental social results for the poor have not yet been achieved.

The trajectory of social housing policy in Brazil: From the National Housing Bank to the Ministry of the Cities

This paper discusses social housing policy in Brazil since the 1990s by analyzing government programs’ institutional arrangements, their sources of revenues and the formatting of related financial systems. The conclusion suggests that all these arrangements have not constituted a comprehensive housing policy with the clear aim of serving to enhance housing conditions in the country. Housing ‘policies’ since the 1990s – as proposed by Fernando Collor de Mello, Itamar Franco, Fernando Henrique Cardoso and ´ Luis Inacio Lula da Silva’s governments (in the latter case, despite much progress towards subsidized investment programs) – have sought to consolidate financial instruments in line with global markets, restructuring the way private interests operate within the system, a necessary however incomplete course of action. Different from rhetoric, this has resulted in failure as the more fundamental social results for the poor have not yet been achieved.