Analysis of UV and EUV emission from impacts on the Sun after 2011 June 7 eruptive flare

On 2011 June 7 debris from a large filament eruption fell back to the Sun causing bright ultraviolet (UV) and extreme ultraviolet (EUV) splashes across the surface. These impacts may give clues on the process of stellar accretion. The aim is to investigate how the impact emission is influenced by structures in the falling ejecta and at the solar surface. We determine the UV and EUV light curves of a sample of impacts. The ballistic impact velocity is estimated from the ejection and landing times and, where possible, compared with the velocity derived by tracking the downflows in SDO/AIA and STEREO/EUVI images. Estimates of the column density before impact are made from the darkness of the falling plasma in the 193 A channel. The impact velocities were between 230 and 450 km/s. All impacts produced bright EUV emission at the impact site but bright UV was only observed when the impacting fragments reached the chromosphere. There was no clear relation between EUV intensity and kinetic energy. Low UV to EUV intensity ratios (I{UV}/I{EUV}) were seen (i) from impacts of low column-density fragments, (ii) when splashes, produced by some impacts, prevented subsequent fragments from reaching the chromosphere, and (iii) from an impact in an active region. The earliest impacts with the lowest velocity (~250 km/s) had the highest I{UV}/I{EUV}. The I{UV}/I{EUV} decreases with impact velocity, magnetic field at the impact site, and EUV ionising flux. Many of the infalling fragments dissipate above the chromosphere either due to ionisation and trapping in magnetic structures, or to them encountering a splash from an earlier impact. If the same happens in accreting stars then the reduced X-ray compared to optical emission that has been observed is more likely due to absorption by the trailing stream than locally at the impact site.Comment: 10 pages, 14 figures To be published in A&

The Relationship between Future Self-Continuity and Mobile Phone Dependence of College Students: Mediating Role of Self-Control

The problem of mobile phone dependence is becoming more and more serious. Therefore, it is very important to explore the causes of mobile phone dependence and its psychological mechanism. One of the important characteristics of mobile phone dependence is the loss of control, which shows that self-control is an important factor affecting mobile phone dependence. Self-continuity is closely related to cell phone dependence. Mobile phone addicts usually use mobile phones to temporarily relieve the pressure and negative emotions, but it will lead to more pressure and negative emotions in the future. In order to examine the situation of college students’ future self-continuity, self-control and mobile phone addiction as well as their relationships, especially mediating effect of self-control, a total of 482 college students were assessed with Future Self-Continuity Scale (FSC), Self-Control Scale (SCS), and Mobile Phone Dependency Index (MPAI). The results showed that: (1) The future self-continuity, self-control and mobile phone dependence of the college students in this study were all at a medium level, and there was no significant difference in demographic variables (such as gender, grade, etc.); (2) Both future self-continuity and self-control were negatively correlated with mobile phone dependence; (3) There was a significant positive correlation between future self-continuity and self-control; (4) Self-control played a partial mediating role between future self-continuity and mobile phone dependence. Therefore, improving self-continuity and self-control can be an effective way to intervene mobile phone dependence. In addition research implication, limitations and future directions were discussed

Frequency response-based damage identification by minimum constitutive relation error and sparse regularization

The objective of this paper is to provide a new damage identification method using frequency response data. In this approach, the inverse identification problem is treated as a nonlinear optimization problem whose objective function is just the constitutive relation error (CRE). To circumvent the ill-posedness of the inverse problem which is caused by use of the possibly insufficient data and enhance the robustness of the identification process, the sparse regularization is introduced where the ℓ1-norm regularization term is added to the original CRE function. In regard to the minimum solution of the sparse-regularized CRE objective function, the alternating minimization (AM) method is established. The attractive features of the present damage identification approach are: (a) while coping with the sparse regularization, a closed-form solution is obtained due to the decoupling of the CRE function with respect to the damage parameters and hence the sparse regularization term would introduce little computational complexity; (b) the sparse regularization parameters are directly determined by a simple threshold setting method; (c) no sensitivity analysis is involved herein. Numerical examples are conducted to verify the proposed approach and the results show that the sparse regularization obviously improves the accuracy and robustness for the identified damages