With the exponential growth of online social network services such as Facebook and Twitter, social networks and social medias become more and more important, directly influencing politics, economics, and our daily life. Mining big social networks aims to collect and analyze web-scale social data to reveal patterns of individual and group behaviors. It is an inherently interdisciplinary academic field which emerged from sociology, psychology, statistics, and graph theory. In this article, I briefly survey recent progress on social network mining with an emphasis on understanding the interactions among users in the large dynamic social networks. I will start with some basic knowledge for social network analysis, including methodologies and tools for macro-level, meso-level and microlevel social network analysis. Then I will give an overall roadmap of social network mining. After that, I will describe methodologies for modeling user behavior including state-of-the-art methods forlearning user profiles, and introduce recent progress on modeling dynamics of user behaviors using deep learning. Then I will present models and algorithms for quantitative analysis on social interactions including homophily and social influence.Finally, I will introduce network structure model including social group formation, and network topology generation. We will introduce recent developed network embedding algorithms for modeling social networks with the embedding techniques. Finally, I will use several concrete examples from Alibaba, the largest online shopping website in the world, and WeChat, the largest social messaging service in China, to explain how online social networks influence our offline world.

Human exploration and development of space is being pursued by spacefaring nations to explore, use, and enable the development of space and expand the human experience there. The goals include: increasing human knowledge of nature’s processes using the space environment; exploring and settling the solar system; achieving routine space travel; and enriching life on Earth through living and working in space. A crucial aspect of future space missions is the development of infrastructure to optimize safety, productivity, and costs. A major component of mission execution is operations management. NASA’s International Space Station is providing extensive experience in both infrastructure and operations. In view of this, a vigorously organized approach is needed to implement successful space-, planet-, and ground-based research and operations that entails wise and efficient use of technical and human resources. Many revolutionary technologies being pursued by researchers and technologists may be vital in making space missions safe, reliable, cost-effective, and productive. These include: ionic polymer–metal composite technology; solid-state lasers; time-domain sensors and communication systems; high-temperature superconductivity; nanotechnology; variable specific impulse magneto plasma rocket; fuzzy logic; wavelet technology; and neural networks. An overview of some of these will be presented, along with their application to space missions.

The dynamic analogue of the von Karman equations is used to study the forced response, including asymmetric vibrations and traveling waves, of a clamped circular plate subjected to harmonic excitations when the frequency of excitation is near one of the natural frequencies. The method of multiple scales, a perturbation technique, is used to solve the non-linear governing equations. The approach presented provides a great deal of insight into the nature of the non-linear forced resonant response. It is shown that in the absence of internal resonance (i.e., a combination of commensurable natural frequencies) or when the frequency of excitation is near one of the lower frequencies involved in the internal resonance, the steady state response can only have the form of a standing wave. However, when the frequency of excitation is near the highest frequency involved in the internal resonance it is possible for a traveling wave component of the highest mode to appear in the steady state response.