63 resultados para Metodos formais


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In this study, two circadian related centres, the suprachiasmatic nucleus (SCN) and the intergeniculate leaflet (IGL) were evaluated in respect to their cytoarchitecture, retinal afferents and chemical content of major cells and axon terminals with a tract tracer and immunohistochemical techniques in the rock cavy (Kerodon rupestris), a Brazilian caviidae rodent species. The rock cavy SCN is innervated in its ventral portion by terminals from the predominantly contralateral retina. It also contains neurophisin and vasoactive intestinal polypeptide immunoreactive cell bodies and neuropeptide Y and enkephalin immunopositive fibres and terminals and is marked by intense GFAP immunoreactivity. The IGL receives a predominantly contralateral retinal projection, contains neuropeptide Y and nitric oxide synthase producing neurons and enkephalin immunopositive terminals and is characterized by dense GFAP immunoreactivity. This is the first report examining the neural circadian system in a crepuscular rodent species for which circadian properties have been described. The results are discussed comparing with what has been described for other species and in the context of the functional significance of these centres

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The purpose of this work is to map the family and community social supports for adolescents and young students from Bom Pastor Distric, West Zone of Natal/RN, as well as to describe how such resources are used by these individuaIs in that community. Social support refers not only to formal activities or organizations, but also to spontaneous or informal forms of support - friendship and solidarity nets available in the community, affective relations that are meaningful in the lives of children and young people. Our discussion is based on a research performed with 382 adolescents and young students from Jean Mermoz Public School (students from 5th to 11th grades, aged 13 to 14). We emphasized the situations of violence derived from family or community spheres faced by these students. In relation to this specific aspect, we observed the participants more frequently look for help from the informal social supports, mostly from their friends, which indicates that the formal ones are not considered to be effective instruments for social assistance. The search for informal social supports shows the relations informally established in the streets (for instance when they look for help from friends, rei atives or neighbors) have more effect and play an important role in which there are values and affections exchange. Thinking the strengthening of these social links is of extreme importance and leads to the weakening of the hegemonic logics focused on the production of subjects as private identities, and to the amplification of an ethics committed to the disassembly of a sociability anchored to fear, impotence, intolerance, discrimination, and reduction of spaces for circulating and confronting mechanisms of social exclusion. It is crucial that we concentrate our attention to building friendship as a system of reciprocity and affective exchanges, as a space for political actions and production of forms of lives that are potent against social anesthesia

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This paper discusses the expression of informality in contemporary capitalism. Thematic of relevance to the analysis of the reality of work today and the logic that moves the capital, its real presence in the lives of individuals. The street trading of Pau dos Ferros town, popularly known as "street market" was chosen as the search space. The main objective is to seize and examine the articulations and logic, present in the configuration of the street trading of this city, located in the state of Rio Grande do Norte, explaining the functionality of informality for capitalist accumulation, but also for the reproduction of segments of the working class. Our analysis is based in the perspective of totality, trying to grasp the historical determinations of the phenomenon in focus. It includes the analysis of the mechanisms used by the capital to reproduce itself in the current historical context, which has been implicated in the composition of the labor markets of different countries and in various forms of exploitation to which workers in general are subject. It also means discussing the development of capitalism in Brazil, the logic that permeates its dependence, and especially the use of over-exploitation of labor, as a lever for internal accumulation. The course of investigation consisted of theoretical research to form the basis of theoretical and methodological analysis and to outline the context in which our research object is inserted, and field research conducted in two phases: systematic observation, which allowed to map traders features and the infrastructure of commerce, and the conduction of interviews with key informants. The material collected was scrutinized according to analytical scheme inspired by the content analysis. Among the main considerations developed from the research process we include: the street trading of Pau dos Ferros remains shrouded in the majority sale of agricultural products, this demonstrates the structural characteristics of the region. However, the supply of this product is no longer restricted to the excess of small local producers. The presence of the dealer changed the distribution of the product, streamlining it. In parallel, business practices are developed, practices in which traded goods (industrial) reflect the moment of capitalist restoration, a larger business network. The reflections also made it possible to show that street trading follows developing on the basis of informal work, which gains functionality to the system, as it is configured as a space commonly used to drain part of the production, of industries (clothing/shoes), especially if the distribution is considered as an essential element of the complex process that aims at capital appreciation. This activity has been functioning as a place of employment and income generation for the subjects who are away from formal employment, masking, this way, unemployment, moreover, they allow them to continue as consumers. Such expressions reflect the ability and the logic of capital to expand and aggregate into so many realities. It is underway today, the logic that has led many workers to join the project of domination of capital, by the illusory chance to become capitalists. The aim has been to turn the subject into a consumer and the worker an enterprising

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Smart card applications represent a growing market. Usually this kind of application manipulate and store critical information that requires some level of security, such as financial or confidential information. The quality and trustworthiness of smart card software can be improved through a rigorous development process that embraces formal techniques of software engineering. In this work we propose the BSmart method, a specialization of the B formal method dedicated to the development of smart card Java Card applications. The method describes how a Java Card application can be generated from a B refinement process of its formal abstract specification. The development is supported by a set of tools, which automates the generation of some required refinements and the translation to Java Card client (host) and server (applet) applications. With respect to verification, the method development process was formalized and verified in the B method, using the Atelier B tool [Cle12a]. We emphasize that the Java Card application is translated from the last stage of refinement, named implementation. This translation process was specified in ASF+SDF [BKV08], describing the grammar of both languages (SDF) and the code transformations through rewrite rules (ASF). This specification was an important support during the translator development and contributes to the tool documentation. We also emphasize the KitSmart library [Dut06, San12], an essential component of BSmart, containing models of all 93 classes/interfaces of Java Card API 2:2:2, of Java/Java Card data types and machines that can be useful for the specifier, but are not part of the standard Java Card library. In other to validate the method, its tool support and the KitSmart, we developed an electronic passport application following the BSmart method. We believe that the results reached in this work contribute to Java Card development, allowing the generation of complete (client and server components), and less subject to errors, Java Card applications.

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Formal methods should be used to specify and verify on-card software in Java Card applications. Furthermore, Java Card programming style requires runtime verification of all input conditions for all on-card methods, where the main goal is to preserve the data in the card. Design by contract, and in particular, the JML language, are an option for this kind of development and verification, as runtime verification is part of the Design by contract method implemented by JML. However, JML and its currently available tools for runtime verification were not designed with Java Card limitations in mind and are not Java Card compliant. In this thesis, we analyze how much of this situation is really intrinsic of Java Card limitations and how much is just a matter of a complete re-design of JML and its tools. We propose the requirements for a new language which is Java Card compliant and indicate the lines on which a compiler for this language should be built. JCML strips from JML non-Java Card aspects such as concurrency and unsupported types. This would not be enough, however, without a great effort in optimization of the verification code generated by its compiler, as this verification code must run on the card. The JCML compiler, although being much more restricted than the one for JML, is able to generate Java Card compliant verification code for some lightweight specifications. As conclusion, we present a Java Card compliant variant of JML, JCML (Java Card Modeling Language), with a preliminary version of its compiler

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Java Card technology allows the development and execution of small applications embedded in smart cards. A Java Card application is composed of an external card client and of an application in the card that implements the services available to the client by means of an Application Programming Interface (API). Usually, these applications manipulate and store important information, such as cash and confidential data of their owners. Thus, it is necessary to adopt rigor on developing a smart card application to improve its quality and trustworthiness. The use of formal methods on the development of these applications is a way to reach these quality requirements. The B method is one of the many formal methods for system specification. The development in B starts with the functional specification of the system, continues with the application of some optional refinements to the specification and, from the last level of refinement, it is possible to generate code for some programming language. The B formalism has a good tool support and its application to Java Card is adequate since the specification and development of APIs is one of the major applications of B. The BSmart method proposed here aims to promote the rigorous development of Java Card applications up to the generation of its code, based on the refinement of its formal specification described in the B notation. This development is supported by the BSmart tool, that is composed of some programs that automate each stage of the method; and by a library of B modules and Java Card classes that model primitive types, essential Java Card API classes and reusable data structures

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Some programs may have their entry data specified by formalized context-free grammars. This formalization facilitates the use of tools in the systematization and the rise of the quality of their test process. This category of programs, compilers have been the first to use this kind of tool for the automation of their tests. In this work we present an approach for definition of tests from the formal description of the entries of the program. The generation of the sentences is performed by taking into account syntactic aspects defined by the specification of the entries, the grammar. For optimization, their coverage criteria are used to limit the quantity of tests without diminishing their quality. Our approach uses these criteria to drive generation to produce sentences that satisfy a specific coverage criterion. The approach presented is based on the use of Lua language, relying heavily on its resources of coroutines and dynamic construction of functions. With these resources, we propose a simple and compact implementation that can be optimized and controlled in different ways, in order to seek satisfaction the different implemented coverage criteria. To make the use of our tool simpler, the EBNF notation for the specification of the entries was adopted. Its parser was specified in the tool Meta-Environment for rapid prototyping

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With the increasing complexity of software systems, there is also an increased concern about its faults. These faults can cause financial losses and even loss of life. Therefore, we propose in this paper the minimization of faults in software by using formally specified tests. The combination of testing and formal specifications is gaining strength in searches mainly through the MBT (Model-Based Testing). The development of software from formal specifications, when the whole process of refinement is done rigorously, ensures that what is specified in the application will be implemented. Thus, the implementation generated from these specifications would accurately depict what was specified. But not always the specification is refined to the level of implementation and code generation, and in these cases the tests generated from the specification tend to find fault. Additionally, the generation of so-called "invalid tests", ie tests that exercise the application scenarios that were not addressed in the specification, complements more significantly the formal development process. Therefore, this paper proposes a method for generating tests from B formal specifications. This method was structured in pseudo-code. The method is based on the systematization of the techniques of black box testing of boundary value analysis, equivalence partitioning, as well as the technique of orthogonal pairs. The method was applied to a B specification and B test machines that generate test cases independent of implementation language were generated. Aiming to validate the method, test cases were transformed manually in JUnit test cases and the application, created from the B specification and developed in Java, was tested. Faults were found with the execution of the JUnit test cases

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This dissertation aims at extending the JCircus tool, a translator of formal specifications into code that receives a Circus specification as input, and translates the specification into Java code. Circus is a formal language whose syntax is based on Z s and CSP s syntax. JCircus generated code uses JCSP, which is a Java API that implements CSP primitives. As JCSP does not implement all CSP s primitives, the translation strategy from Circus to Java is not trivial. Some CSP primitives, like parallelism, external choice, communication and multi-synchronization are partially implemented. As an aditional scope, this dissertation will also develop a tool for testing JCSP programs, called JCSPUnit, which will also be included in JCircus new version. The extended version of JCircus will be called JCircus 2.0.

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The use of increasingly complex software applications is demanding greater investment in the development of such systems to ensure applications with better quality. Therefore, new techniques are being used in Software Engineering, thus making the development process more effective. Among these new approaches, we highlight Formal Methods, which use formal languages that are strongly based on mathematics and have a well-defined semantics and syntax. One of these languages is Circus, which can be used to model concurrent systems. It was developed from the union of concepts from two other specification languages: Z, which specifies systems with complex data, and CSP, which is normally used to model concurrent systems. Circus has an associated refinement calculus, which can be used to develop software in a precise and stepwise fashion. Each step is justified by the application of a refinement law (possibly with the discharge of proof obligations). Sometimes, the same laws can be applied in the same manner in different developments or even in different parts of a single development. A strategy to optimize this calculus is to formalise these application as a refinement tactic, which can then be used as a single transformation rule. CRefine was developed to support the Circus refinement calculus. However, before the work presented here, it did not provide support for refinement tactics. The aim of this work is to provide tool support for refinement tactics. For that, we develop a new module in CRefine, which automates the process of defining and applying refinement tactics that are formalised in the tactic language ArcAngelC. Finally, we validate the extension by applying the new module in a case study, which used the refinement tactics in a refinement strategy for verification of SPARK Ada implementations of control systems. In this work, we apply our module in the first two phases of this strategy

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Formal methods and software testing are tools to obtain and control software quality. When used together, they provide mechanisms for software specification, verification and error detection. Even though formal methods allow software to be mathematically verified, they are not enough to assure that a system is free of faults, thus, software testing techniques are necessary to complement the process of verification and validation of a system. Model Based Testing techniques allow tests to be generated from other software artifacts such as specifications and abstract models. Using formal specifications as basis for test creation, we can generate better quality tests, because these specifications are usually precise and free of ambiguity. Fernanda Souza (2009) proposed a method to define test cases from B Method specifications. This method used information from the machine s invariant and the operation s precondition to define positive and negative test cases for an operation, using equivalent class partitioning and boundary value analysis based techniques. However, the method proposed in 2009 was not automated and had conceptual deficiencies like, for instance, it did not fit in a well defined coverage criteria classification. We started our work with a case study that applied the method in an example of B specification from the industry. Based in this case study we ve obtained subsidies to improve it. In our work we evolved the proposed method, rewriting it and adding characteristics to make it compatible with a test classification used by the community. We also improved the method to support specifications structured in different components, to use information from the operation s behavior on the test case generation process and to use new coverage criterias. Besides, we have implemented a tool to automate the method and we have submitted it to more complex case studies

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The development of smart card applications requires a high level of reliability. Formal methods provide means for this reliability to be achieved. The BSmart method and tool contribute to the development of smart card applications with the support of the B method, generating Java Card code from B specifications. For the development with BSmart to be effectively rigorous without overloading the user it is important to have a library of reusable components built in B. The goal of KitSmart is to provide this support. A first research about the composition of this library was a graduation work from Universidade Federal do Rio Grande do Norte, made by Thiago Dutra in 2006. This first version of the kit resulted in a specification of Java Card primitive types byte, short and boolean in B and the creation of reusable components for application development. This work provides an improvement of KitSmart with the addition of API Java Card specification made in B and a guide for the creation of new components. The API Java Card in B, besides being available to be used for development of applications, is also useful as a documentation of each API class. The reusable components correspond to modules to manipulate specific structures, such as date and time. These structures are not available for B or Java Card. These components for Java Card are generated from specifications formally verified in B. The guide contains quick reference on how to specify some structures and how some situations were adapted from object-orientation to the B Method. This work was evaluated through a case study made through the BSmart tool, that makes use of the KitSmart library. In this case study, it is possible to see the contribution of the components in a B specification. This kit should be useful for B method users and Java Card application developers

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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

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The component-based development of systems revolutionized the software development process, facilitating the maintenance, providing more confiability and reuse. Nevertheless, even with all the advantages of the development of components, their composition is an important concern. The verification through informal tests is not enough to achieve a safe composition, because they are not based on formal semantic models with which we are able to describe precisally a system s behaviour. In this context, formal methods provide ways to accurately specify systems through mathematical notations providing, among other benefits, more safety. The formal method CSP enables the specification of concurrent systems and verification of properties intrinsic to them, as well as the refinement among different models. Some approaches apply constraints using CSP, to check the behavior of composition between components, assisting in the verification of those components in advance. Hence, aiming to assist this process, considering that the software market increasingly requires more automation, reducing work and providing agility in business, this work presents a tool that automatizes the verification of composition among components, in which all complexity of formal language is kept hidden from users. Thus, through a simple interface, the tool BST (BRIC-Tool-Suport) helps to create and compose components, predicting, in advance, undesirable behaviors in the system, such as deadlocks

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