Estudo da viabilidade da destilação solar para polimento de águas produzidas de petróleo

This work study of solar distillation feasibility in effluent of petroleum industry: produced water, making possible your reuse for irrigation of oleaginous cultures or fodder crops or in steam generation, as well the transport phenomena involved. The methodology for development of this project was to characterize the effluent to be treated and to accomplish physical and chemical analysis in the distilled, to build distillation equipment, concomitant operation of both equipments and implementation of data processing and economical evaluation. The methodology used for all parameters is outlined in APHA (1998) and sampling of the type compound. The feeding of distillation equipment was performed with treated effluent from UTPF of Guamaré. The temperature was monitored throughout the distillers and during the time of operation. The distillers feed occur, as a rule, for sifon. The distillers were operated by a period of 17 months between July 2007 and February 2009, in which 40 experiments were performed. The radiation and temperature datas were acquired in the INPE s site and the temperature inside of the distillers was registered by DATALOGGER Novus. The rates of condensation (mL / min) were determined by measuring of the flow in a graduate test tube of 10 mL and a chronometer. We used two simple solar effect distillers of passive type with different angles in coverage: 20 ° and 45 °. The results obtained in this study and the relevant discussions are divided into six topics: sample characterization and quality of distilled; construction of distillers; operation (data, temperature profile), climatic aspects, treatment of data and economical analysis. Results obtained can be inferred that: the energy loss by the adoption of vessel glass was not significant, however, complicates the logistics of maintenance the equipment on a large scale. In the other hand, the surface of the tub with a glass shield on the equipment deterioration, both devices showed similar performance, so there is not justified for use of equipment 450. With regard to the climatological study it was verified that the Natal city presents monthly medium radiation varying in a range between 350 and 600 W/m2, and medium of wind speed of 5 m / s. The medium humidity is around 70% and rainfall is very small. The regime of the system is transient and although it has been treated as a stationary system shows that the model accurately represents the distillers system's 20 degrees. The quality of the distilled with regard to the parameters evaluated in this study is consistent with the Class 3 waters of CONAMA (Resolution 357). Therefore we can conclude that solar distillation has viability for treat oilfield produced water when considered the technical and environmental aspects, although it is not economically viable

Avaliação do potencial fitorremediador da mamona (Ricinus communis L.) e girassol (Helianthus annuus L.) quanto à remoção de chumbo e tolueno em efluentes sintéticos.

The development of research that aim to reduce or even eliminate the environmental impacts provided by anthropogenic actions. One of these main action is the discard of industrial waste in the biotic compartments such as soil, water and air, gained more space in academic settings and in private. A technique of phytoremediation involving the use of plants (trees, shrubs, creepers and aquatic) and their associated microorganisms in order to remove, degrade or isolate toxic substances to the environment. This study aimed to evaluate the potential for phytoremediation of castor bean (Ricinus communis L.) and sunflower (Helianthus annuus L.), wild crops suitable region of Rio Grande do Norte, to reduce concentrations of lead and toluene present in synthetic wastewater that simulate the characteristics of treated water production originated in the petrochemical Guamaré. The experiment was accomplished in randomized blocks in four replicates. Seeds of BRS Energy for the development of seedlings of castor beans and sunflower for Catissol 01, both provided by EMPARN (Empresa de Pesquisa Agropecuária do Rio Grande do Norte) were used. Lead concentrations tested were 250, 500 and 1000 mg/L called T2, T3 and T4, respectively, for toluene the concentrations used were 125, 256 and 501 μg/L, called T5, T6 and T7, respectively. The data for removal of lead in relation to sewage systems applied in castor bean and sunflower were 43.89 and 51.85% (T2), 73.60 and 73.74% (T3) and 85.66 and 87.80 % (T4), respectively, and toluene were approximately 52.12 and 25.54% (T5), 55.10 and 58.05% (T6) and 79.77 and 74.76% (T7) for castor and sunflower seeds, respectively. From the data obtained, it can be deduce that mechanisms involved in reducing the contaminants were of phytoextraction, in relation to lead and phytodegradation for toluene. However, it can be concluded that the castor bean and sunflower crops can be used in exhaust after-treatment of industrial effluents that have this type of contaminant

Atividades experimentais no ensino de biologia em escolas públicas do estado do Rio Grande do Norte, Brasil: caracterização geral e concepção de professores

Recent research has revealed that the majority of Biology teachers believe the practice of experimental activities as a didactical means would be the solution for the improvement of the Biology teaching-learning process. There are, however, studies which signal the lack of efficiency in such practice lessons as far as building scientific knowledge is concerned. It is also said that despite the enthusiasm on the teachers‟ part, such classes are rarely taught in high school. Several studies point pedagogical difficulties as well as nonexistence of a minimal infrastructure needed in laboratories as cause of low frequency in experimental activities. The poor teacher performance in terms of planning and development of classes; the large number of students per class; lack of financial stimulus for teachers are other reasons to be taken into account among others, in which can also be included difficulties of epistemological nature. That means an unfavorable eye of the teacher towards experimental activities. Our study aimed to clarify if such scenario is generalized in high schools throughout the state of Rio Grande do Norte Brazil. During our investigation a sample of twenty teaching institutions were used. They were divided in two groups: in the first group, five IFRN- Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Norte schools. Two of those in Natal, and the other three from the country side. The second group is represented by fifteen state schools belonging to the Natal metropolitan area. The objectives of the research were to label schools concerning laboratory facilities; to identify difficulties pointed by teachers when performing experiment classes, and to become familiar with the conceptions of the teachers in regarding biology experiment classes. To perform such task, a questionnaire was used as instrument of data collecting. It contained multiple choice, essay questions and a semi-structured interview with the assistance of a voice recorder. The data analysis and the in loco observation allowed the conclusion that the federal schools do present better facilities for the practice of experimental activities when compared to state schools. Another aspect pointed is the fact that teachers of federal schools have more time available for planning the experiments; they are also better paid and are given access a career development, which leads to better salaries. All those advantages however, do not show a significantly higher frequency regarding the development of experiments when compared to state school teachers. Both teachers of federal and state schools pointed infra-structure problems such as the availability of reactants, equipments and consumption supplies as main obstacle to the practice of experiments in biology classes. Such fact leads us to conclude that maybe there are other problems not covered by the questionnaire such as poor ability to plan and execute experimental activities. As far as conceptions about experimental activities, it was verified in the majority of the interviewees a inductive-empiric point of view of science possibly inherited during their academic formation and such point of view reflected on the way they plan and execute experiments with students

O ensino por problemas nos livros de química: uma análise do conteúdo estrutura atômica

La enseñanza de problemas se ha investigado en la didáctica de las ciencias naturales como un medio importante para desarrollar el aprendizaje de los conocimientos científicos y la formación de competencias básicas. Dada la importancia de los libros de texto para la enseñanza de la ciencia, con el fin de verificar el enfoque de la enseñanza con problemas en los libros de química, se procedió a una investigación realizada en las obras aprobadas en PNLD 2012, basado en el método de Análisis de Contenido. Se analizó el contenido de la estructura atómica, como marco teórico la perspectiva de la enseñanza problémica, basada en el materialismo histórico y dialéctico. Metodológicamente la investigación presenta un carácter cualitativo. Los resultados del análisis de contenido corroboraron la cuestiones de estudio iniciales relacionadas con la explicación centrándose en los problemas, lo que permitió inferir la elaboración de una Unidad Didactica basada en los métodos problémicos para la enseñanza de los modelos atómicos por la exposición problémica, la conversación heurística y la busca parcial, como forma de aproximar los estudiantes a la naturaleza de las ciencias naturales y contribuir al desarrollo de actitudes positivas en el aprendizaje de la química

Processos de construção do sentido na esquizofrenia: uma perspectiva cognitiva da linguagem

There is still a lot to be said about the relationship between culture, cognition and language. Within an embodied cognition perspective to language, it may be understood that the senses generated and used in discourse are built and negotiated not only linguistically, since they also involve stereotypes, schemes, frames, etc. These cognitive structures, in turn, would emerge from subjects experiences and interactions with a sociohistorically constituted environment. With that in mind, what would happen if someone had an altered view in the perception of such environment? The objective of this master s thesis was to understand the process of meaning construction, aiming at the activation of frames, in the discourse of people who have been diagnosed as schizophrenic and have been hospitalized, that is, individuals who have their socio-environmental perception affected. With that aim in mind, a speech corpus was generated with three schizophrenic patients from Professor Severino Lopes Psychiatric Hospital. The data were collected and analyzed qualitatively, based on the theoretical and analytical premises of Cognitive Linguistics, more specifically, of Simulation Semantic perspective. Therefore, it was possible to identify aspects related to meaning construction processes in the discourse of schizophrenic patients, understanding that language is integrated with cognition and culture. Therefore, the alteration in the way experiences are perceived by schizophrenic patients affect the linguistic production of these subjects. Finally, if we take into consideration that the mental disturbance caused by schizophrenia results in a change in perception of reality by these individuals, we can infer an implication of such factors in language and, subsequently, the interference of such issues in the meaning construction processes in the discourse of patients diagnosed with schizophrenia

A interface entre educação e mercado : uma análise crítica das mudanças socioculturais no contexto educacional

In the context of late modernity, the socio-cultural transformations established new social practices which corroborate discursive changes in dialectic movements, contributing to the order of the educational discourses to be more and more affected by typical market discourses and values which are covered by ideologies, hegemonic struggles and power relations. In this sense, this research study, which is based on the theoretical tenets of the Critical Discourse Analysis in its interdisciplinary branch (FAIRCLOUGH, 2006; ORMUNDO, 2010; PEDROSA, 2010; RAMALHO E RESENDE, 2011), aims at discussing how the sociocultural changes in the context of private education interact with the market proposal of neoliberal and economical policies. The research was methodologically based on the qualitative approach (CHIZZOTTI, 1991; BOGDAN e BIKLEN, 1994; MINAYO, 1994), especially on the principles of contemporary Applied Linguistics (SIGNORINI, 1998; MOITA-LOPES, 2006; MENEZES, SILVA, GOMES, 2009). Data were gathered from advertisements used in campaigns by private educational institutions and agencies in Natal/RN; the advertisements were collected in primary and secondary levels and in language courses from October to December, 2010. The data analysis indicate that education, in the context of globalization and late modernity, has become a market agency and that the new face of the educational discourse of private institutions is interwoven with a social representation of education as a site of struggle and hegemonic dispute. Therefore, the research leads us to infer that, as the educational public policies based on hegemonic economy and on ideological assumptions of international agents (Global Bank, FMI, etc.) have become widespread, education has become an arena of dispute and a powerful economic product to the market of cultural and commercial industry, thus emphasizing a society in which everything is economically based

A esfera como metáfora: representações do futebol no campo da literatura (leituras do tema no conto de ficção)

Football, understood as a phenomenon of sports practice and nearly universal coverage, can also be seen as a game whose operation circumvents the cultural universe of people who practice it. Much more than just a sport, so this game is a cultural phenomenon par excellence, bearing a communicational and aesthetic dimension whose occurrence has been spotted in various fields of scientific and cultural. Therefore, it is as game and as a phenomenon of culture, we intend to focus on football here as an object of study. Our aim is to investigate the sport in Brazil taking the Literature and Journalism as privileged instances of their representation in the media. Thus, the central idea of this research is to show when and how football has become a recurrent theme in Brazilian literature, starting with its journalistic approach until we get an overview of the aesthetic representation of the game, Literature as the main focus of attention and taking the genre of fiction story as material fact of their representation. With this approach, we intend to develop an overall view, overview of the literature about football in our country and at the same time, particularize this vision in some representative authors of it, like the writer-journalist Mario Filho (the historian, essayist on the modernization of chronic specific theme), José Lins do Rego (writer passionate about the game), Nelson Rodrigues (the esthetician that elevated the sport to the status of art by chronic), Lima Barreto (who along with Antonio de Alcantara Machado pioneered the formalized within the fiction) and the storytellers of the topic itself. In the end, we intend to infer the results of evaluations and reviews of books and authors listed, we have examined a wide sense, but also vertical (and which were focused on a socio-historical perspective and critical-aesthetic) within the assumption that seems be a homology between the way football practice amongst us will historically winning characteristics as to form a Brazilian school of football, and how our writers, journalists will be addressing the topic, which also would focus on creating a "Brazilian way" of telling literary football. The proof of this hypothesis operational work together with the development of historiography and the necessity arising from it, creating a "Guide to Reading football theme in fictional tale of Brazil" shut the focal perspective of this study

Padrões cariotípicos em tetraodontiformes (Osteichthypes) :redução genômica e mecanismos de diversificação

The Tetraodontiformes order is composed for about 400 species of fish, distributed in ten families, with circuntropical distribution. The morphologic diversity of each family reflects in, part, the different levels of specialization. This group represents an ancestry after-Perciformes and constitutes the last branch of the diffusion of the Teleósteos, occupying a position of prominence. The phylogenetics relationships of the Tetraodontiformes exist diverse works examining and, in all, these families are recognized as groups brothers, being Diodontidae next to Tetraodontidae and Balistidae next to Monacanthidae. Although it possesss a representative number of species, the works involving of the families Balistidae and Monacanthidae are few exemplary, especially species of oceanic islands. In this work cytogenetic studies in five species had been analyzed Cantherhines macrocerus, Cantherhines pullus (Monacanthidae), Melichthys niger (Balistidae), Sphoeroides testudíneus (Tetraodontidae) and Chilomycterus antennatus (Diodontidae); through conventional coloration, Ag-NORs and C banding. Ahead of the different karyological trends of evolution presented by the Tetraodontiformes, the present work also searched to verify the relation existence enters the total size of the chromosomes with the amount of DNA in these groups of Tetraodontiformes. For such, they had been correlated the total size of the chromosomes of these species, with values of content of available DNA in literature. The cytogenetics analyses for the species C.macrocerusJ C.pullus (Monacanthidae) and M.niger (Balistidae), had disclosed 40 chromosomes, all acrocentrics. All possess only one pair of NORs and pericentromeric heterochromatin. For S.testudíneus the found dyploid number was equal 2n=46, with NF=78 (16m+18sm+8st+4a), while that for C.antennatus it possesss 2n=50, with NF=76 (4m+22st+24a). Both species possess simple NORs and pericentromeric heterochromatin blocks. In M.niger, the presence of positive marking (heterochromatin and NOR) in the secondary constriction in the second chromosomic pair suggesting the occurrence of a rearrangement, possibly a fusing involving these homologous ones, indicating that these events had been important for the establishment of the karyological history of this group. A maintenance of the chromosomic constancy found in the populations of C.macrocerus (Monacanthidae) and S.testudineus (Tetraodontidae) perhaps if must for the aiding of the gene flow through oceanic chains. These data contrast with the differentiated kinds of chromosomes of C.antennatus between the Northeast coast and Southeastern, suggesting that the ecological standards of each species, added to the conditions of the marine environment, can be responsible for the karyological delineation of each species. The found characteristics for the species C.macrocerus, C.pullus, M.niger, S.testudineus and C.antennatus add it the available data for other species of Tetraodontiformes. From the data gotten in the present study, it can be inferred that the DNA content possesss direct relation with the total length of the chromosomes

Imunoexpressão do EGFR e da podoplanina em cistos radiculares e dentígeros

The radicular cysts (RCs) and dentigerous (DCs), despite having different etiologies, form a pathological cavity lined by epithelium, which grows due to the buildup of fluid inside, as the surrounding bone is reabsorbed and the epithelium will being induced to proliferate. The epithelial proliferation, which has been identified as one of the key processes in the growth of odontogenic cystic lesions, is influenced by growth factors such as EGFR (epidermal growth receptor factor) and podoplanin (PDPN), many of which may have its production stimulated mainly during inflammatory processes. The objective of this research was to evaluate and compare the immunohistochemical expression of EGFR and PDPN in 30 cases of RCs and 30 cases of DCs, semiquantitatively, in light microscopy, associating it with the degree of inflammation, cellular localization of immunostaining and with the immunostained epithelial layers. Data were statistically analyzed by Chi-square test and Fisher exact test, considering a significance level of 5 %. The results showed high immunoreactivity of both proteins in the lesions studied, only statistically significant difference was observed in immunostaining of PDPN (p=0.033), which proved higher in RCs. The other analyzed parameters showed no relevant significant differences. We conclude that, as EGFR and PDPN showed high immunoreactivity in cystic lesions analyzed, these proteins participate the pathogenesis of these lesions through the epithelial stimulation process, despite having different etiologies. Furthermore, it can infer that the higher immunostaining of PDNP in RCs that DCs showed no distinction indicator between the two lesions, regarding their etiologies, once this protein also showed a considerable expression in DCs, independent of the intensity of the inflammatory infiltrate

Investigação da influência do cochilo na aprendizagem escolar

There is a known positive effect of nocturnal sleep for brain plasticity and the consolidation of declarative and procedural memories, as well as for the facilitation of insight in problem solving. However, a possible pro-mnemonic effect of daytime naps after learning is yet to be properly characterized. The goal of this project was to evaluate the influence of daytime naps on learning among elementary and middleschool students, measuring the one-day (acute), and semester-long (chronic) effects of post-learning naps on performance. In the Acute Day-Nap condition, the elementary students were exposed to a class and then randomly divided into three groups: Nap (N), Game-based English Class (GBEC) and Traditional English Class (TEC). There were 2 multiple-choice follow-up tests to evaluate students performance in the short and long runs. In the short run, the N group outperformed the other two groups; and such tendency was maintained in the long run. In the chronic condition, the middle-school students were randomly separated into two groups: Nap (N) and Class (C) and were observed during one academic term. The N group had increased school performance in relation to the C group. In the statistical analyses, independent t-tests were applied considering the scores significant when p<0,05, expressed in terms of average ± average standard error. Results can be interpreted as an indication that a single daytime nap opportunity is not enough to ensure learning benefits. Therefore, more research is needed in order to advocate in favor of a daytime nap as a pedagogical means of promoting enhanced school performance

Síntese e caracterização de carreadores de oxigênio para combustão com recirculação química obtidos via reação de combustão assistida por microondas

Perovskites oxides win importance by its properties and commercials applications, they have a high thermal stability, have conductive properties, electrical, catalytic, electro catalytic, optical and magnetic, and are thermally stable. Because of these properties, are being widely studied as carriers of oxygen in the process of power generation with CO2 capture. In this work, the base carrier system La1-xMexNiO3 (Me = Ca and Sr) were synthesized by the method via the combustion reaction assisted by microwave. were synthesized from the combustion reaction method by microwave process. This method control the synthesi`s conditions to obtain materials with specific characteristics. The carriers calcined at 800 ° C/2h were analyzed by thermal analysis (TG-DTA), to verify its thermal stability, X-ray diffraction (XRD) to verify the phase formation, with subsequent refinement by the Rietveld method, to quantify the percentage of phases formed, the surface area by BET method was determined, scanning electron microscopy (SEM) was obtained to evaluate the material morphology and temperature programmed reduction (TPR) was done to observe the metallic phase of the nickel. After all proposed characterization and analysis of their results can be inferred to these oxides, key features so that they can be applied as carriers for combustion reactions in chemical cycles. The final products showed perovskite-type structures K2NiF4 (main) and ABO3.

Complexos metálicos de cobalto, níquel e cobre com a Pirazina-2-carboxamida e 4- hidrazida ácida piridincarboxílica: síntese e caracterização

This work involved the synthesis, characterization and proposing the molecular structure of coordination compounds involving ligands pyrazine-2-carboxamide (PZA) and 4- hydrazide acidic pyridine carboxylic (INH) and metals of the first transition series (M = Co2+, Ni2+ and Cu2+). For the characterization of the compounds used were analytical techniques such as infrared absorption spectroscopy average (FT-IR) molar conductivity measurements, CHN elemental analysis, EDTA Complexometric, measurement of melting point, X-ray diffraction by powder method, Thermogravimetry (TG) and Differential Thermal Analysis (DTA) and Simultaneous Differential Scanning Calorimetry (DSC). The absorption spectra in the infrared region suggested that the ligand coordination to the metal center occurs through the carbonyl oxygen atom and nitrogen alpha pyrazine ring to those complexes formed with PZA. For INH complexes with metal-ligand coordination is through the carbonyl oxygen and nitrogen of the terminal hydrazide grouping. The conductivity measurements of the complexes in aqueous solution they suggest to all behavior of the type 1:2 electrolytes, and conduct of non-electrolytes in acetonitrile. The results obtained by CHN elemental analysis and EDTA Complexometric allowed to infer the stoichiometry of the compounds synthesized. For all of the complexes obtained was possible to record the melting points, neither of which melted near the melting temperature of the free ligands. The X-ray diffraction showed that the complexes of pyrazinamide exhibited diffraction lines, suggesting that these compounds are crystalline, while compounds of isoniazid, with the exception of cobalt, exhibited diffraction lines, indicating that they are crystalline. The results from the TG-DTA and DSC allowed information regarding the dehydration and thermal decomposition of these complexes

A produção das desigualdades: análise da relação entre trabalho infantil e indicadores sociais

The International Labor Organization (OIT) estimates that there are around 118 million children subjected to child labor around the world. In Brazil, there are 3.5 million workers aged between 5 and 17. This exploitation practice constitutes a serious social problem, including of Public Health, since these workers are exposed to a wide range of risks, such as those related to health, physical integrity and even to life, which may cause them to become sick adults and/or interrupt their lives prematurely. Therefore, this research aims to investigate the relationship between the frequency of child labor in the age group of 10 to 13 years and some socio-economic indicators. It is a quantitative research in an ecological study whose levels of analysis are the Brazilian municipalities grouped in 161 regions, defined from socioeconomic criteria. The dependent variable of this study was the prevalence of child labor in the age group of 10 to 13 years. The independent variables were selected after a correlation between the 2010 Census of child labor in the age group of 10 to 13 years and secondary data had been conducted, adopting two main independent variables: funds from the Family Allowance Program (PBF) per 1,000 inhabitants and Funds from the Child Labor Eradication Program (PETI) per a thousand inhabitants. Initially, it was conducted a descriptive analysis of the variables of the study, then, a bivariate analysis, and the correlation matrix was built. At last, the Multiple Linear Regression stratified analysis was performed. The results of this survey indicate that public policies , like the Bolsa Familia Program Features per 1000 inhabitants and Resources Program for the Eradication of Child Labour to be allocated to municipalities with HDI < 0.697 represent a decrease in the rate of child labor ; These programs have the resources to be invested in municipalities with HDI > = 0.697 have no effect on the rate of child labor. Other adjustment variables showed significance, among these the municipal Human Development Index (IDH), years of schooling at 18 years of age, illiteracy at 15 years of age or more, employees without employment contract at 18 years of age and the Gini Index. It is understood that the child labor issue is complex. The problem is associated, although not restricted to, poverty, the social exclusion and inequality that exist in Brazil, but other factors of cultural and economic nature, as well as of organization of production, also account for its aggravation. Fighting child labor involves a wide intersectoral articulation, shared and integrated with several public policies, among them health, sports, culture, agriculture, labor and human rights, with a view to guaranteeing the integrality of the rights of children and adolescents in situation of labor and of their respective families

As pessoas com deficiência no mercado de trabalho: expressão das desigualdades sociais

This work was developed in the extent of the Post Graduation Program in Social Service of the Federal University of Rio Grande do Norte. It talks about the process of inclusion of the disabled people in the Job market in Mossoró-RN, bringing for the academic debate relevant thematic for the Brazilian society, for the profession of Social Service and similar areas and for the people with deficiency. It has the objective to apprehend the determiners that make possible the process of the disabled people's inclusion in the Job market in Mossoró, having as parameter the National Politics for the Integration of People Bearers of Deficiency. The critical theoretical perspective is backed in Marx's ideas for the understanding concerning the work, as well as in Pochamann, concerning the job market, regarding the exclusion/inclusion category is based in Martins, Yasbek and Sposati and on deficiency in the National Politics for the Integration of the Disabled People. The research is of qualitative nature and it took as subjects 26 (twenty-six) people, being 09 (nine) people with deficiency, inserted in the formal job and regulated market, and 17 (seventeen) managers of private companies and public institutions of the city of Mossoró-RN. For the collection of data we used techniques of nonsystemic observation, semi-structured interview and documental analysis. The results of the research mark that any modality of the human workforce used in the current context, they are functional to the capitalism and they move forward towards exploration, alienation and subordination of the work to the capital; the National Politics for the Integration of the People with Deficiency expresses and reproduces the contradictory dynamics of the class society, it reflects the neo liberal shades through the selectivity and of the articulation among the federated beings and organizations of the civil society for its operational system; there is a misproportion between the percentages of the quotas and the amount of people with deficiency inserted in the job market, just corresponding to a tiny numeric magnitude; the developed activities are of low social status and it is expressive the amount of workers that receives between one and two minimum wages. These data drive us to infer that the mentioned politics make possible, partly, the inclusion of the disabled people in the job market, though, such inclusion is executed in the selective or focused dimensions, marginal, precarious and unstable

Deciding difference logic in a Nelson-Oppen combination framework

O método de combinação de Nelson-Oppen permite que vários procedimentos de decisão, cada um projetado para uma teoria específica, possam ser combinados para inferir sobre teorias mais abrangentes, através do princípio de propagação de igualdades. Provadores de teorema baseados neste modelo são beneficiados por sua característica modular e podem evoluir mais facilmente, incrementalmente. Difference logic é uma subteoria da aritmética linear. Ela é formada por constraints do tipo x − y ≤ c, onde x e y são variáveis e c é uma constante. Difference logic é muito comum em vários problemas, como circuitos digitais, agendamento, sistemas temporais, etc. e se apresenta predominante em vários outros casos. Difference logic ainda se caracteriza por ser modelada usando teoria dos grafos. Isto permite que vários algoritmos eficientes e conhecidos da teoria de grafos possam ser utilizados. Um procedimento de decisão para difference logic é capaz de induzir sobre milhares de constraints. Um procedimento de decisão para a teoria de difference logic tem como objetivo principal informar se um conjunto de constraints de difference logic é satisfatível (as variáveis podem assumir valores que tornam o conjunto consistente) ou não. Além disso, para funcionar em um modelo de combinação baseado em Nelson-Oppen, o procedimento de decisão precisa ter outras funcionalidades, como geração de igualdade de variáveis, prova de inconsistência, premissas, etc. Este trabalho apresenta um procedimento de decisão para a teoria de difference logic dentro de uma arquitetura baseada no método de combinação de Nelson-Oppen. O trabalho foi realizado integrando-se ao provador haRVey, de onde foi possível observar o seu funcionamento. Detalhes de implementação e testes experimentais são relatados