881 research outputs found
Empirical research on the evaluation model and method of sustainability of the open source ecosystem
The development of open source brings new thinking and production modes to software engineering and computer science, and establishes a software development method and ecological environment in which groups participate. Regardless of investors, developers, participants, and managers, they are most concerned about whether the Open Source Ecosystem can be sustainable to ensure that the ecosystem they choose will serve users for a long time. Moreover, the most important quality of the software ecosystem is sustainability, and it is also a research area in Symmetry. Therefore, it is significant to assess the sustainability of the Open Source Ecosystem. However, the current measurement of the sustainability of the Open Source Ecosystem lacks universal measurement indicators, as well as a method and a model. Therefore, this paper constructs an Evaluation Indicators System, which consists of three levels: The target level, the guideline level and the evaluation level, and takes openness, stability, activity, and extensibility as measurement indicators. On this basis, a weight calculation method, based on information contribution values and a Sustainability Assessment Model, is proposed. The models and methods are used to analyze the factors affecting the sustainability of Stack Overflow (SO) ecosystem. Through the analysis, we find that every indicator in the SO ecosystem is partaking in different development trends. The development trend of a single indicator does not represent the sustainable development trend of the whole ecosystem. It is necessary to consider all of the indicators to judge that ecosystem’s sustainability. The research on the sustainability of the Open Source Ecosystem is helpful for judging software health, measuring development efficiency and adjusting organizational structure. It also provides a reference for researchers who study the sustainability of software engineering
Scalarization of Kerr-Newman black holes in the Einstein-Chern-Simons-scalar theory
We investigate the tachyonic instability of Kerr-Newman (KN) black hole with
a rotation parameter in the Einstein-Chern-Simons-scalar theory coupled
with a quadratic massive scalar field. This instability analysis corresponds to
exploring the onset of spontaneous scalarization for KN black holes. First, we
find no -bound for case by considering (1+1)-dimensional
analytical method. A direct numerical method is adopted to explore
(2+1)-dimensional time evolution of a massive scalar perturbation with positive
and negative to obtain threshold curves numerically. We obtain
threshold curves of tachyonic instability for positive
without any -bounds. We expect to find the same threshold curves
of tachyonic instability for negative without any
-bound because its linearized scalar theory is invariant under the
transformation of and . In addition, it
is found that the scalar mass term suppresses tachyonic instability of KN black
holes.Comment: 18 pages, 4 figures, minor change
Poly[di-μ2-azido-μ3-pyrazine-2-carboxylÂato-cadmium(II)]
The title compound, [Cd(C5H3N2O2)(N3)]n, has been preÂpared by the reaction of pyrazine-2-carboxylic acid, cadmium(II) nitrate and sodium azide. In the structure, the CdII atom is six-coordinated by two azide anions and three pyrazine-2-carboxylÂate ligands. Each pyrazine-2-carboxylÂate ligand bridges three CdII atoms, whereas the azide ligand bridges two CdII atoms, resulting in the formation of a two-dimensional metal–organic polymer developing parallel to the (100) plane
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