4,192 research outputs found
Automatic Detection of Public Development Projects in Large Open Source Ecosystems: An Exploratory Study on GitHub
Hosting over 10 million of software projects, GitHub is one of the most
important data sources to study behavior of developers and software projects.
However, with the increase of the size of open source datasets, the potential
threats to mining these datasets have also grown. As the dataset grows, it
becomes gradually unrealistic for human to confirm quality of all samples. Some
studies have investigated this problem and provided solutions to avoid threats
in sample selection, but some of these solutions (e.g., finding development
projects) require human intervention. When the amount of data to be processed
increases, these semi-automatic solutions become less useful since the effort
in need for human intervention is far beyond affordable. To solve this problem,
we investigated the GHTorrent dataset and proposed a method to detect public
development projects. The results show that our method can effectively improve
the sample selection process in two ways: (1) We provide a simple model to
automatically select samples (with 0.827 precision and 0.947 recall); (2) We
also offer a complex model to help researchers carefully screen samples (with
63.2% less effort than manually confirming all samples, and can achieve 0.926
precision and 0.959 recall).Comment: Accepted by the SEKE2018 Conferenc
Relativistic Astronomy. III. Test of Special Relativity via Doppler Effect
The Breakthrough Starshot program is planning to send transrelativistic probes to travel to nearby stellar systems within decades. Because the probe velocity is designed to be a good fraction of the light speed, Zhang & Li recently proposed that these transrelativistic probes can be used to study astronomical objects and to test special relativity. In this work, we propose some methods to test special relativity and constrain photon mass using the Doppler effect with the images and spectral features of astronomical objects as observed in the transrelativistic probes. We introduce more general theories to set up the framework of testing special relativity, including the parametric general Doppler effect and the Doppler effect with massive photons. We find that by comparing the spectra of a certain astronomical object, one can test Lorentz invariance and constrain photon mass. Additionally, using the imaging and spectrograph capabilities of transrelativistic probes, one can test time dilation and constrain photon mass. For a transrelativistic probe with velocity v ~ 0.2c, aperture D ~ 3.5 cm, and spectral resolution R ~ 100 (or 1000), we find that the probe velocity uncertainty can be constrained to σ v ~ 0.01c (or 0.001c), and the time dilation factor uncertainty can be constrained to (or 0.001), where is the time dilation factor and γ is the Lorentz factor. Meanwhile, the photon mass limit is set to m γ 10−33 g, which is slightly lower than the energy of the optical photon
- …