On the Common Envelope Efficiency

In this work, we try to use the apparent luminosity versus displacement (i.e., $L_{\rm X}$ vs. $R$) correlation of high mass X-ray binaries (HMXBs) to constrain the common envelope (CE) efficiency $\alpha_{\rm CE}$, which is a key parameter affecting the evolution of the binary orbit during the CE phase. The major updates that crucial for the CE evolution include a variable $\lambda$ parameter and a new CE criterion for Hertzsprung gap donor stars, both of which are recently developed. We find that, within the framework of the standard energy formula for CE and core definition at mass $X=10$\%, a high value of $\alpha_{\rm CE}$, i.e., around 0.8-1.0, is more preferable, while $\alpha_{\rm CE}< \sim 0.4$ likely can not reconstruct the observed $L_{\rm X}$ vs. $R$ distribution. However due to an ambiguous definition for the core boundary in the literature, the used $\lambda$ here still carries almost two order of magnitude uncertainty, which may translate directly to the expected value of $\alpha_{\rm CE}$. We present the detailed components of current HMXBs and their spatial offsets from star clusters, which may be further testified by future observations of HMXB populations in nearby star-forming galaxies.Comment: 14 pages, 10 figures, 7 tables, accepted for publication in MNRA

Design of a Bicycle-Based Real-Time Information Feedback System

[[abstract]]In recent years, cycling has rapidly emerged as a city sport. Although bicycles have various functions, they fail to provide cyclists with sufficient cycling-related information and post cycling analysis. Extant bicycle devices can provide cyclists with partial cycling-related information but cannot provide fully integrated information. In addition, these devices cannot perform post cycling analysis or cycling information sharing. Therefore, this paper proposes a bicycle-based real-time information feedback system, which is used to integrate and provide various types of real-time information for cyclists and help them achieve their desired cycling results. After cycling, the cyclists could view cycling-related information through software analysis. The information included cycling routes taken, total cycling distance, and total calories burned. The proposed system also saved information related to cycling routes such as acceleration, deceleration, directional changes, and slope changes. By analyzing the recorded information, cyclists not only gained further insight into their cycling results but also were able to share cycling-related information through the Internet, which would benefit cyclists who has not cycled along this road before. Finally, we hope the proposed system could provide cyclists with real-time, accurate, and complete information, and enabling them to enjoy a perfect cycling environment.[[notice]]補正完