RefDiff: Detecting Refactorings in Version Histories

Refactoring is a well-known technique that is widely adopted by software engineers to improve the design and enable the evolution of a system. Knowing which refactoring operations were applied in a code change is a valuable information to understand software evolution, adapt software components, merge code changes, and other applications. In this paper, we present RefDiff, an automated approach that identifies refactorings performed between two code revisions in a git repository. RefDiff employs a combination of heuristics based on static analysis and code similarity to detect 13 well-known refactoring types. In an evaluation using an oracle of 448 known refactoring operations, distributed across seven Java projects, our approach achieved precision of 100% and recall of 88%. Moreover, our evaluation suggests that RefDiff has superior precision and recall than existing state-of-the-art approaches.Comment: Paper accepted at 14th International Conference on Mining Software Repositories (MSR), pages 1-11, 201

A docência presencial e on-line e o desafio comunicacional da cibercultura

[Resumo] A docência interativa presencial e online é demanda da cibercultura, isto é, do novo ambiente comunicacional que surge com a interconexão mundial de computadores em forte expansão no início do século 21, novo espaço de comunicação, de sociabilidade, de organização, de informação, de conhecimento e de educação. O professor acostumado ao primado da transmissão na educação e na mídia de massa tem agora o desafio de educar na cibercultura. Terá que desenvolver sua imaginação criadora para atender as novas demandas sociais de aprendizagem interativa. Interatividade é a modalidade comunicacional que ganha centralidade na cibercultura. Exprime a disponibilização consciente de um plus comunicacional de modo expressamente complexo presente na mensagem e previsto pelo emissor, que abre ao receptor a possibilidades de responder ao sistema de expressão e de dialogar com ele. Grande salto qualitativo em relação ao modo de comunicação de massa que prevaleceu até o final do século XX, o modo de comunicação interativa ameaça a lógica unívoca da mídia de massa, oxalá como superação do constrangimento da recepção passiva. Este texto reúne diversas sugestões sistematizadas como “indicadores de interatividade” capazes de redimensionar a prática docente presencial e online. Com esses indicadores o professor poderá rever sua autoria na construção da aprendizagem, transformando o ambiente de comunicação, tornando possível a transição de um modelo centrado na seqüência linear, que encadeia unidirecionalmente graus, idades e pacotes de conhecimento, a outro descentrado e plural, cuja chave é o encontro do texto e o hipertexto. Para tanto, o professor precisará se dar conta do desafio comunicacional da cibercultura e do perfil comunicacional dos aprendizes que aprenderam com o controle remoto e com a lógica unívoca da mídia de massa e agora aprendem com o mouse e com as “janelas” móveis que permitem mais do que meramente assisti

Improved electromagnetic compatibility standards for the interconnected wireless world

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The future is wireless, a world where everything is interconnected. However, the current standards for ensuring the electromagnetic compatibility (EMC) and the coexistence of such wireless systems urge for a major update. It is shown how novel statistical approaches based on the amplitude probability distribution detector and time-domain measurements are better suited for estimating the degradation caused by electromagnetic interferences on digital communication systems than the established practice of determining compliance according to the quasi-peak detector levels using a pass/fail criterion. Therefore, a redefinition of the test methods and of the compliance requirements in terms of EMC standards must be a priority of the international standardization bodies. Finally, a discussion of the fundamental challenges involved in this standardization breakthrough for EMC is delivered.Postprint (author's final draft

Identifying Unmaintained Projects in GitHub

Background: Open source software has an increasing importance in modern software development. However, there is also a growing concern on the sustainability of such projects, which are usually managed by a small number of developers, frequently working as volunteers. Aims: In this paper, we propose an approach to identify GitHub projects that are not actively maintained. Our goal is to alert users about the risks of using these projects and possibly motivate other developers to assume the maintenance of the projects. Method: We train machine learning models to identify unmaintained or sparsely maintained projects, based on a set of features about project activity (commits, forks, issues, etc). We empirically validate the model with the best performance with the principal developers of 129 GitHub projects. Results: The proposed machine learning approach has a precision of 80%, based on the feedback of real open source developers; and a recall of 96%. We also show that our approach can be used to assess the risks of projects becoming unmaintained. Conclusions: The model proposed in this paper can be used by open source users and developers to identify GitHub projects that are not actively maintained anymore.Comment: Accepted at 12th International Symposium on Empirical Software Engineering and Measurement (ESEM), 10 pages, 201