Yuan Meng

Ocean covers 70.8% of the Earth’s surface, and it plays an important role in supporting all life on Earth. Nonetheless, more than 80% of the ocean’s volume remains unmapped, unobserved and unexplored. In this regard, Underwater Sensor Networks (USNs), which offer ubiquitous computation, efficient communication and reliable control, are emerging as a promising solution to understand and explore the ocean. In order to support the application of USNs, accurate position information from sensor nodes is required to correctly analyze and interpret the data sampled. However, the openness and weak communication characteristics of USNs make underwater localization much more challenging in comparison to terrestrial sensor networks. In this book, we focus on the localization problem in USNs, taking into account the unique characteristics of the underwater environment. This problem is of considerable importance, since fundamental guidance on the design and analysis ofUSN localization is very limited at present. To this end, we first introduce the network architecture of USNs and briefly review previous approaches to the localization of USNs. Then, the asynchronous clock, node mobility, stratification effect, privacy preserving and attack detection are considered respectively and corresponding localization schemes are developed. Lastly, the book’s rich implications provide guidance on the design of future USN localization schemes. The results in this book reveal from a system perspective that underwater localization accuracy is closely related to the communication protocol and optimization estimator. Researchers, scientists and engineers in the field of USNs can benefit greatly from this book, which provides a wealth of information, useful methods and practical algorithms to help understand and explore the ocean.

Ocean covers 70.8% of the Earth’s surface, and it plays an important role in supporting all life on Earth. Nonetheless, more than 80% of the ocean’s volume remains unmapped, unobserved and unexplored. In this regard, Underwater Sensor Networks (USNs), which offer ubiquitous computation, efficient communication and reliable control, are emerging as a promising solution to understand and explore the ocean. In order to support the application of USNs, accurate position information from sensor nodes is required to correctly analyze and interpret the data sampled. However, the openness and weak communication characteristics of USNs make underwater localization much more challenging in comparison to terrestrial sensor networks. In this book, we focus on the localization problem in USNs, taking into account the unique characteristics of the underwater environment. This problem is of considerable importance, since fundamental guidance on the design and analysis ofUSN localization is very limited at present. To this end, we first introduce the network architecture of USNs and briefly review previous approaches to the localization of USNs. Then, the asynchronous clock, node mobility, stratification effect, privacy preserving and attack detection are considered respectively and corresponding localization schemes are developed. Lastly, the book’s rich implications provide guidance on the design of future USN localization schemes. The results in this book reveal from a system perspective that underwater localization accuracy is closely related to the communication protocol and optimization estimator. Researchers, scientists and engineers in the field of USNs can benefit greatly from this book, which provides a wealth of information, useful methods and practical algorithms to help understand and explore the ocean.

This true story of the Bai Family in China traces how their devotion to truth placed them on a collision course with the Communist Party. When they became practitioners of Falun Gong, it paved the way for a painful and torturous, yet enlightening, path in life, especially for the two brilliant brothers Xiaojun and Shaohua. After the Chinese Communist regime began its systematic repression of Falun Gong practitioners in 1999, Bai Xiaojun was tortured to death in one of the laogai or "re-education through labour" camps. His brother Bai Shaohua also disappeared in another such prison for three years. Through blood and sweat, Shaohua made it alive out of prison but was once again abducted in early February, 2008. The details in this gripping account of how Falun Gong practitioners are being repressed reveal the larger pattern of life, and death, under a totalitarian regime. Authors Long Tu and Yuan Meng, now living in Canada, compiled this account through personal contact with members of the Bai Family. They also write from personal experience. Long Tu is a computer program designer and Yuan Meng an architect and urban designer. Yuan Meng was herself imprisoned for 16 months in a laogai camp before leaving China, where unusual "meals" caused her body to swell and her back bones were broken during the persecution. They now live in Toronto and wrote Pagoda of Light to honour their imprisoned friends, noting that "the experience of the Bai family is but one of thousands of examples."