A Systems Dynamics Simulation Study of Network Public Opinion Evolution Mechanism

The factors that affect formation and dissemination of public opinion have been studied for a long time. However, the findings are disparate and fragmented, given the characteristics of netizens and new media in the Big Data era. To this end, this article introduces eight mechanisms working on formation and dissemination of public opinion on network. Based on system dynamics, this article further proposes a comprehensive causal relationship model to explore the factors affecting the consequence of public opinion on network. Particularly, the role of government is taken into consideration in this model. A simulation with Vensim PLE is conducted. The results of the simulation indicate that group polarization among netizens, opinion leaders, the quantity of media audience, the frequency of media report, government attention, and warning mechanism for public opinion crisis affect the consequence of public opinion on network significantly. Implications of the findings are discussed

A UNIFIED TIMING AND SPECTRAL MODEL FOR THE ANOMALOUS X-RAY PULSARS XTE J1810-197 AND CXOU J164710.2-455216

Anomalous X-ray pulsars (AXPs) and soft gamma repeaters (SGRs) are two small classes of X-ray sources strongly suspected to host a magnetar, i.e. an ultra-magnetized neutron star with $B\approx 10^14-10^15 G. Many SGRs/AXPs are known to be variable, and recently the existence of genuinely "transient" magnetars was discovered. Here we present a comprehensive study of the pulse profile and spectral evolution of the two transient AXPs (TAXPs) XTE J1810-197 and CXOU J164710.2-455216. Our analysis was carried out in the framework of the twisted magnetosphere model for magnetar emission. Starting from 3D Monte Carlo simulations of the emerging spectrum, we produced a large database of synthetic pulse profiles which was fitted to observed lightcurves in different spectral bands and at different epochs. This allowed us to derive the physical parameters of the model and their evolution with time, together with the geometry of the two sources, i.e. the inclination of the line-of-sight and of the magnetic axis with respect to the rotation axis. We then fitted the (phase-averaged) spectra of the two TAXPs at different epochs using a model similar to that used to calculate the pulse profiles ntzang in XSPEC) freezing all parameters to the values obtained from the timing analysis, and leaving only the normalization free to vary. This provided acceptable fits to XMM-Newton data in all the observations we analyzed. Our results support a picture in which a limited portion of the star surface close to one of the magnetic poles is heated at the outburst onset. The subsequent evolution is driven both by the cooling/varying size of the heated cap and by a progressive untwisting of the magnetosphere.Comment: 15 pages, 12 figures, accepted for publication in Ap