Fig. 1. Schematic diagram of gas leakage source mobile measurement

Fig. 2. Physical image of non-dispersive infrared CO₂ sensor system

Fig. 3. Physical image of off-axis integrating cavity output spectrum infrared CH₄ sensor

Fig. 4. Basic flowchart of fireworks algorithm

Fig. 5. Flowchart of improved fireworks algorithm

Fig. 6. Changes in A_D and C_V values of two algorithms under different wind speed conditions in different dimensions. (a) Changes in A_D and C_V values of FUFWA-x and FWA-x; (b) changes in A_D and C_Vvalues of FUFWA-y and FWA-y; (c) changes in A_D and C_V values of FUFWA-z and FWA-z; (d) changes in A_D and C_Vvalues of FUFWA-d and FWA-d

Fig. 7. Changes in A_D and C_V values of two algorithms under different wind direction conditions in different dimensions. (a) Changes in A_D and C_V values of FUFWA-x and FWA-x; (b) changes in A_D and C_Vvalues of FUFWA-y and FWA-y; (c) changes in A_D and C_V values of FUFWA-z and FWA-z; (d) changes in A_D and C_V values of FUFWA-d and FWA-d

Fig. 8. Changes in A_D and C_V values of two algorithms under different numbers of monitoring nodes in different dimensions. (a) Changes in A_D and C_V values of FUFWA-x and FWA-x; (b) changes in A_D and C_V values of FUFWA-y and FWA-y; (c) changes in A_D and C_V values of FUFWA-z and FWA-z; (d) changes in A_D and C_Vvalues of FUFWA-d and FWA-d

Fig. 9. Time required for single run of FUFWA and FWA

Fig. 10. Photos of measurement device and fire source in on-site experiment on campus of Jilin University

Fig. 11. On-site experiment positioning maps. (a) Mobile radius r=3 m; (b) mobile radius r=7 m; (c) mobile radius r=12 m; (d) mobile radius r=17 m

Fig. 12. On site experimental diagram of 3D spatial gas source localization. (a) Schematic diagram of experimental setup; (b) on site experimental diagram

Fig. 13. Changes in CH₄ gas volume fraction during the experiment

Fig. 14. Positioning map of three-dimensional space gas source positioning experiment. (a) Positioning map of three-dimensional space gas source positioning experiment; (b) Baidu map for three-dimensional space gas source localization experiment