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Environmental monitoring, public safety, safe production, and other areas all benefit greatly from the use of gas detection technologies. The infrared image of a gas could be used to determine its type from a long distance in gas detection. The infrared image can show the spatial distribution of the gas cloud and the background, allowing for long-distance and non-contact detection during safety production and hazardous chemical accident rescue. In this study, a gas detection system based on multispectral infrared imaging is devised, which can detect a variety of gases and determine the types of gas by separating the infrared radiation. It is made up of an imaging optical system, an uncooled focal plane detector, a filter controller, and a data gathering and processing system. The resolution of the infrared image is 640 × 512 and the working band of the system is 6.5~15 μm. The system can detect traces of pollutants in ambient air or gas clouds at higher concentrations. Ammonia, sulfur hexafluoride, methane, sulfur dioxide, and dimethyl methyl phosphonate were all successfully detected in real time. Ammonia clouds could be detected at a distance of 1124.5 m.

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This paper presents a new current sensor based on fluxgate principle. The sensor consists of a U-shaped magnetic gathering shell. In the designed sensor, the exciting winding and the secondary winding are arranged orthogonally, so that the magnetic fields produced by the two windings are mutually orthogonal and decoupled. Introducing a magnetic gathering shell into the sensor is to concentrate the detected magnetic field and to reduce the interference of an external stray field. Based on the theoretical analysis and the simulation results, a prototype was designed. Test results show that the proposed sensor can measure currents up to 25 A, and has an accuracy of 0.6% and a remarkable resolution.Index Terms-Current sensor, fluxgate principle, toroidal magnetic core, U-shaped magnetic gathering shell.