USE OF A VIEWER BOX IN SECCIII DISK MEASUREMENTS1

We used a closed-ended viewer box in the measurement of Secchi depth and compared the results with simultaneous naked-eye measurements. We have shown that use of such a viewer box increases Secchi depth measurement by removing the interfering effects of water surface glare and glitter. A viewer box also increases between-observer precision. Measurements made both with and without the viewer box are slightly greater on the shady side of the boat than on the sunny side; the latter is the preferred side if Secchi data are to be related to other optical properties. As expected, the difference between viewer box and naked eye measurements increases with increasing wave height but not with increasing illuminance. Because of the lack of uniformity in the way Secchi depth is estimated, and the inherent optical problems with current Secchi depth procedures, an appeal is made for production of a standardized protocol for Secchi observations, including the use of a closed-ended viewer box on the sunny side of the boat.     

Backtracking and prospect on LNG supply chain safety

The safety issues of Liquefied Natural Gas (LNG) in production, storage, loading/unloading, transportation/shipping, and re-gasification have became a major concern, since an accident in the LNG industry would be very costly. Understanding the threat of LNG not only contributes to the process safety and reliability in the research and development (R&D) system, but improves the efficiency of loss prevention, fire protection and emergency responses. As of April 2019, in order to obtain the present status and trend of LNG safety research, basing 1122 documents of the Web of Science database about safety research of LNG as a data source, CiteSpace and VOS viewer were used for network knowledge map analysis. A comprehensive knowledge map of LNG safety field was obtained from several research aspects including scientific research power, research hot spots and trends, research knowledge base and frontier. According to the study results, the development of LNG safety research was divided into four stages from 1970s to 2019, China and South Korea made a lot of contributions, and the United States is the most influential. Among them, the research from 2005 to 2019 was the most representative. Current research results indicate that a combination of Formal Safety Assessment (FSA) methodology and Dynamic Procedure for Atypical Scenarios Identification (DyPASI) will fully identify risks; The PHAST and TerEx programs quickly define safety zones. Computational Fluid Dynamics (CFD) software package can provide accurate quantitative data for the study of LNG safety. Research on quantitative risk assessment (QRA) and LNG evaporated gas (BOG) has been a hot topic and trend in this field. The application of expansion foam in LNG accident mitigation covers most of the research content in this field, and the optimization of LNG liquefaction process has a great influence on this industry. As the international demand for LNG energy output increases, floating liquefied natural gas (FLNG) will have considerable development, and increasingly researchers attach vital importance to the safety of LNG offshore production integrated unit.