Design is often raised in the literature as important to attaining various properties and characteristics in a software system. At least for open-source projects, it can be hard to find evidence of ongoing design work in the technical artifacts produced as part of the development. Although developers usually do not produce specific design documents, they do communicate about design in different ways. In this paper, we provide quantitative evidence that developers address design through discussions in commits, issues, and pull requests. To achieve this, we built a discussions' classifier and automatically labeled 102,122 discussions from 77 projects. Based on this data, we make four observations about the projects: i) on average, 25% of the discussions in a project are about design; ii) on average, 26% of developers contribute to at least one design discussion; iii) only 1% of the developers contribute to more than 15% of the discussions in a project; and iv) these few developers who contribute to a broad range of design discussions are also the top committers in a project.
Change impact analysis techniques that underestimate impact may cause important financial losses from the point of view of an IT services company. Thus, reducing falsenegatives in these techniques is a goal with strong practical relevance. This work presents a technique that uses both static and dynamic analysis of object-oriented source code to improve resulting impact estimates in terms of recall. The technique consists of three steps: static analysis to identify structural dependencies between code entities, dynamic analysis to identify dependencies based on a succession relation derived from execution traces, and a ranking of results from both analyses that takes into account the relevance of dynamic dependencies. Evaluation was performed through prototype development and a multiple-case quantitative case study that compared our solution against a static technique and a dynamic one. Results showed that our hybrid technique improved recall between 90 and 115% compared to the static technique, and between 21.2 and 39% compared to the dynamic one.
Bentonite exhibt a range of industrial applications moving millions of dollars on the market per year. Among several applications if highlights it is use for petroleum drilling fluids. Thus, this work aims to characterize physical, mineralogical and technologically, the bentonitics clays of Sossego County, Paraíba, Brazil. Mineralogical characterization of clays was done through the following techniques: particle size analysis by laser diffraction, thermogravimetric and differential thermal analysis, chemical analysis and x-ray diffraction. The clays were turned in by treatment with sodium in Na2CO3 and then determined whether the apparent viscosity, plastic and volume of filtrate of clay-water dispersions. The results showed that the samples are of polycationic, showing levels of MgO, CaO and K2O, similar to those from Boa Vista County, Paraíba, Brazil, and consist of clay mineral kaolinite, quartz and esmec. The clays showed rheological properties that indicate potential for use in drilling fluids.
New ceramic formulations based on scheelite tailing were developed, and their potential in the ceramic industry was evaluated. Green bodies with different contents of scheelite tailing (0–8 wt%) were sintered (1150 °C, 1200 °C, and 1250 °C) and characterized in terms of the main mineralogical phases, microstructure, and physico-mechanical properties. The mullite was the main phase identified in all sintered temperatures. This result was also ratified with the aid of scanning electron microscope (SEM) images, in which small needles of the mullite were detected. The presence of mullite is required because it contributes to increasing the mechanical resistance of the material. The physico-mechanical properties measured (water absorption, linear shrinkage, apparent porosity, and flexural strength) were compared to the ISO 13006, and the samples sintered at 1150 °C presented potential to be used as semi-stoneware, while those sintered at 1200 °C and 1250 °C can be employed stoneware and porcelain tiles, respectively.
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