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Abstract
Year: 2015 PMID: 26517863 PMCID: PMC4627798 DOI: 10.1371/journal.pone.0140413
Source DB: PubMed Journal: PLoS One ISSN: 1932-6203 Impact factor: 3.240
Fig 1Two networks generated by the CC model.
The functions of the CC model are set to be N(t) = 5, ∣Di∣ = 0.2β(θi)ti for the case in Panel(a), and N(t) = [e0.1t], ∣Di∣ = 0.15β(θi)[e0.1ti] for the case in Panel(b). β(⋅) is given by Equation (2) for both cases.
Fig 2The illustration of the connection mechanisms of the CC model(Panel a) and a causal network on a (1 + 1)-spacetime (Panel b).
The influence region of the CC model is the counterpart of the future light cone.
Fig 3The in- and out-degree distributions of a network generated by the CC model.
The functions of the CC model are set as follows: N(t) = [e0.1t], ∣Di∣ = 0.15β(θi)[e0.1ti], and β(⋅) is given by Equation (2). The fitting functions in Panel (a) are the Poisson distribution f(k) = ake−ak! and the mixture Poisson distribution given byEquation (13). The fitting functions in Panel (b) are the power-law functions f(k) = ak −2 and f(k) = k−γ∑n = 0∞(n+xmin)−γ.
Fig 4The evolutionary trends of the annual paper number and the annual average reference length of some datasets.
The fitting curves for the data between 1946–2012 in Panels(a, b) are f(t) = 5.397 × 10−34e4.23 × 10−2 t (R 2: 0.974, RMSE: 224.2) and f(t) = 0.5085t − 982.6 (R 2: 0.958, RMSE: 2.112) respectively. The fitting curve in Panel(c) is f(t) = 6.038 × 10−88e0.106t(R 2: 0.9828, RMSE: 7249).
Fig 5In-degree distributions of the citation networks in Table 1.
Panels(b, c, e, f) show the fitting effects of the in-degree distributions of the nodes with in-degree larger than 9 by the power-law functions f(k) = ak −2 and f(k) = k−γ∑n = 0∞(n+xmin)−γ.
Fig 6Out-degree distributions of the citation networks in Table 1 and the fitting curves of the distributions.
The fitting model is the mixture generalized Poisson distribution (Equation (14).