The observation and detection of the subsea environment urgently require large-scale and long-term observation platforms. The design and development of subsea AUVs involve three key points: the subsea-adapted main body structure, agile motion performance that adapts to complex underwater environments, and underwater acoustic communication and positioning technology. This paper discusses the development and evolution of subsea AUVs before proposing solutions to underwater acoustic communication and positioning navigation schemes. It also studies key technologies for the agile motion of subsea AUVs and finally gives an example of a solution for implementing underwater AUVs, i.e., the disk-shaped autonomous underwater helicopter (AUH). This paper will provide guidance for the design of subsea AUVs and the development of corresponding observation and detection technologies.

Wireless charging to autonomous underwater vehicle effectively prolongs the attended time and extends the endurance mileage. As the most promising underwater power feeding technique, inductive power transfer is also faced with challenges like the attenuation in seawater, ocean current disturbance etc. Special concerns in terms of power quality, efficiency improvement and mechanical fixing need to be considered when designing the underwater electromagnetic coupling structure. An attenuation model in seawater is established in this paper. The optimal working frequency range is refined for a specific transmission media. Different from the wireless power transfer system in the air, the underwater WPT system features tight coupling between the transmitter and receiver. The optimal range of coupling coefficient needs to be re-designed, as high coupling coefficient incurs frequency splitting and the increase of harmonic component, while low coupling coefficient results in low efficiency. Based on the theoretical analysis, a self-latching coupling structure is proposed with lightweight design on receiver side. System parameters are optimized correspondingly and a 3kW experiment validates the theoretical analysis.

This paper, based on a lecture given during tour undertaken in May 2014 of key railway establishments in China, consists of a brief introduction to the history and comparisons of railways in the UK and China, a description of rail speed-up in the last few decades in the UK, and notes of current high speed trains. Similar brief details are given of high speed in Europe. Brief mention is made of comparative railway safety. The development of high speed rail in China is discussed and the UK High Speed development plan is briefly introduced. The paper concluded that high speed train system has tremendous advantages in increasing the efficiency and convenience of transport without adding to carbon generation. 本文基于作者于2014年5月在中国参观铁路建设成就时的一篇报告而写成。 内容涵盖铁路发展历史简介, 英国和中国铁路的对比, 英国过去数十年间铁路提速情况的说明以及现有高速铁路的介绍。 此外, 本文还详细讨论了欧洲高铁的发展情况和铁路系统安全的分析比较, 并对中国高铁的发展及英国高铁建设计划进行了说明。 得出高速铁路系统在提高能量利用效率、 增加旅客舒适度、 控制碳排放量等方面有显著优势。

In order to mitigate the risk of excessive heavy metal intake, a study was conducted to assess the levels of arsenic (As), cadmium (Cd), chromium (Cr), and lead (Pb) contamination in 23 edible seafood species obtained from markets in Haikou. The findings were analyzed to evaluate the potential health hazards posed to the local population through consumption. The metals were detected via inductively coupled plasma mass spectrometry (ICP-MS) for quantification. The non-carcinogenic and carcinogenic health risks in humans were assessed via target hazard quotient (THQ), combined target hazard quotient (CTHQ), and target cancer risk (TR). The results indicated that the rank order based on the median metal concentration was As > Cd > Cr > Pb. THQ and CTHQ showed that nine seafood species posed a non-carcinogenic risk regarding from As and Cd consumption separately, or the four targeted metals ingestion together. TR assessment indicated that the InAs in all the species presented a carcinogenic risk to coastal residents. The Cd content in bivalves, algae, and several crustacean (Mantis Shrimp, Orchid Crab, Red spot Swimming Crab) and fish species (Japanese Scad, Pacific Saury), and Cr levels in most bivalve species (Razor Clams, White Clams, Fan Shells, Oysters, Blood Clams) presented a carcinogenic risk. The As, Cd, Pb, and Cr levels of seafood in Haikou were assessed species presented a potential health risk. Necessitating stricter risk should be management and detection capability and monitoring will be improved.

This study proposes a model of multiple receivers in resonant wireless power transmission. Based on the dual‐load series‐resonant wireless power transfer system, the expression of system efficiency and its calculation model is achieved using the coupled mode theory. Considering the mutual coupling between loads, the system transmission efficiency is analysed against the intrinsic decay rate and coupling coefficient by Matlab simulation. The diversity effects of introducing aluminium material are analysed by electromagnetic field analysis through JMAG. Base on the principles of the eddy current loss, the laminated aluminium structure is adopted to restore the transmission characteristics effectively. Finally, 96 kHz magnetic resonant wireless power transfer test platform is established to verify the correctness of theoretical analysis.

Wireless power transfer (WPT) has attracted attention from academia and industry in recent years. WPT has natural electrical isolation between primary and secondary side, which ensures safe charging in an underwater environment. This breakthrough technology greatly facilitates the deep-sea power transmission. However, at the current stage the transferred power and energy efficiency level are not up to that of the WPT system in the air. The major concerns include the attenuation is seawater, extreme temperature and pressure conditions, disturbance of ocean currents, and bio-security. Three questions are answered in this paper: first, the expressions of eddy current loss and attenuation of electromagnetic wave in seawater are unified, and the influence of seawater as transmission medium on the WPT system is discussed. Second, the evolution of electromagnetic coupling structure suitable for underwater applications is studied. Third, the loss and heating effects of an underwater WPT system and the corresponding bio-fouling phenomenon are investigated. The questions above were addressed through analysis of electrical properties, coupler structures, and bio-fouling effects of the underwater WPT system. This paper will facilitate the study and research on underwater WPT applications.