力学进展

2013 Vol. 43, No. 4

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Complex systems and emergence: How theory meets reality

GAO Jianbo

2013, 43(4): 359-389. doi: 10.6052/1000-0992-13-046

Abstract(3106)

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Abstract:
Emergent behaviors of complex systems have fascinated mankind for aeons. It is only in recent decades that extensive efforts have been made to quantitatively study them, resulting in important theories and tools such as chaos theory, random fractal theory, and multiscale analyses. This article aims to convey the best practices in this vast field, emphasizing theory meets reality. As illustrative examples, cyber-security, financial crises, river flow dynamics, and world-wide political conflicts will be briefly discussed. Important future research directions will also be outlined.

Nonlinear Dynamics and Control of Large Deployable Space Structures Composed of Trusses and Meshes

Hu Haiyan, Tian Qiang, Zhang Wei, Jin Dongping, Hu Gengkai, Song Yanping

2013, 43(4): 390-414. doi: 10.6052/1000-0992-13-045

Abstract(3581)

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Abstract:
The space industry in China is eager to have the advanced technology of large space structures composed of trusses, cables and meshes. Such a large space structure, deployed on orbit, serves as the large antenna for different space missions. The important scientific basis of the technology is the nonlinear dynamic modeling, analysis and control of those space structures during their deployment and service. This review article surveys the advances in relevant researches and proposes three open problems as following. The first is the flexible multibody dynamics for the deployment of such a space structure, especially the nonlinear dynamic modeling and analysis for the contacts and wraps of mesh under microgravity, the internal impacts in clearance joints, and the coupling between structure deployment and spacecraft attitude. The second is the dynamic analysis of the space structures after deployment and during service, especially the complicated nonlinear vibrations of the flexible structure with numerous backlash joints under periodic thermal impacts. The third is the dynamic control of the space structures after deployment and during service, especially the under-actuated and lower-powered control for structure vibrations and waves.

Gravitational wave detection by space laser interferometry

LUO Ziren, BAI Shan, BIAN Xing, CHEN Gerui, DONG Peng, DONG Yuhui, GAO Wei, GONG Xuefei, HE Jianwu, LI Hongyin, LI Xiangqian, LI Yuqiong, LIU Heshan, SHAO Mingxue

2013, 43(4): 415-447. doi: 10.6052/1000-0992-13-044

Abstract(4412)

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Abstract:
Gravitational wave detection is now more than a mere veri¯cation of Einstein's relativity. It opens a brand-new window to explore gravitational wave astronomy, therefore attracts increasing attention of scientists from all over the world. Focusing on space laser interferometer gravitational wave detection, we give a comprehensive review on its scienti¯c objectives, recent status and key technologies. With arm-length being of million kilometers, a space detector works within a frequency band from 0.1mHz to 10Hz. Its possible sources include compact binary star system, extreme mass ratio inspiral, intermediate mass ratio inspiral, super mass black hole merge, etc. The success of space gravitational wave detection mission requires a pico-meter precision laser interferometer, and a state-of-the-art drag- free control system. Taking European space gravitational wave detector as an example, we analyze space laser interferometer and drag-free control system in detail. The trend and perspective of Chinese space gravitational wave detection mission are also discussed.

2013 Vol. 43, No. 4

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