Traditional seawater chemical oxygen demand (COD) monitoring methods are based on manual operations, which require various operating procedures and long duration of measurement, are prone to secondary pollution and hence unsuitable for in-situ monitoring. In this paper, we developed a prototype of in-situ seawater COD monitoring sensor based on UV-Vis absorption spectroscopy, and integrating it to a buoy for coastal trials. During the trials, several measures were applied to reduce the influence of biofouling, including coating sensor housing with an environment-friendly anti-fouling paint, and designing a motorized underwater wiper for optical window cleaning. The in-situ COD sensor had been continuously working underwater for more than 6 months, obtaining 1536 sets of seawater UV-Vis absorption sectrum.
We developed two underwater fluorimeters (VIS&UV) for in-situ assessments of aquatic fluorescence constituents. Two prototypes had been developed to assess chlorophyll a and BOD5, respectively, and were deployed under a buoy platform for long-term field tests. Design considerations include exciting light use efficiency, weak fluorescence signal detection, ambient light suppression, corrosion resistance and anti-biofouling. The prototypes demonstrated excellent linearity in response to fluorescence emissions in laboratory calibrations and good environment suitability during the field tests. We had obtained a large amount of observational data and maintenance experience.
This paper develops a promising low-priced optical fiber arcing detection system for measuring pantograph-catenary contact-loss. The system collects the ultraviolet light by UV lens. The filter cuts off visible light to reducing environmental disturbance. Ultraviolet light of arcing is transformed to visible one by fluorescent material, which is packaged on the fiber endface and has a high transforming efficiency in ultraviolet band. This optical fiber arcing detection system is equipped with self-checking pulsed light to monitoring the status of the detection system. The arcing energy is estimated by the relationship between the intensity of ultraviolet light and the output voltage signal.
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