## 4 Simulation and Integration Results
### The Spatiotemporal Analysis of Methane Concentration Based on LrGIS  
Based on the proposed integration method, the CFD simulation function is developed on LrGIS platform, which supports the numerical simulation and can display the simulated data on  
Figure 5: Airflow velocity (m/s) profiles at different time points. Figure 6: Methane concentration (_v/v_%) profiles at different time points. the ventilation system map on the basis of coordinate matching, and also facilitate the visualization of additional relevant data. The effective user access, the location-based information, and means of viewing and analyzing for the simulated data are also the main focuses. Thus, the numerical model is integrated with LrGIS platform, of which the query and analysis functions can also be operated based on the numerical simulation results. Figure 7 shows the map of ventilation system of 5# Sijiazhuang coal mine, the study area of 15116 working face in this case is located in the bottom right corner on the map, with the latitude and longitude ranging from 105,800 to 106,020 m and from 67,125 to 67,725 m. The roam and move functions allow users to observe more detailed features on the coal mine map. To demonstrate the applicability of the CFD simulation function in LrGIS platform, the spatiotemporal analysis for our case study is performed. First, based on the specified numerical parameters, the geometry is prepared and lattice is generated, which are then used to perform the numerical simulating procedure. It is noted that the properties of lattices include the lattice ID, material numbers, and the coordinates. The output data of the simulation is saved as a series of time ordered text files, which contains the X, Y coordinates, the airflow velocity, and methane concentration of each lattice. The tool of methane emission analysis in the CFD simulation model allows for us to demonstrate the spatiotemporal distribution of the airflow behavior and methane concentration. By specifying the time point, the corresponding spatiotemporal distribution of the methane concentration can be visualized on the ventilation system map, together with various spatial coal mine layers, including geographical locations of fans, methane sensors and first aid stations, contour line, measured faultage, river and railway, and also the fictitious graticule, as presented in Figure 8. These information provide managers and miners the access to the large quantities of geographic field data, as well as its query and analysis for the location-based information integrated with simulated data. Basically, the managers or decision makers can use the program to perform several queries according to the specifications, such as, (i) basic mine mapping operations integrated with simulated  
Figure 7: Study area of the ventilation system map in 15# Sijiazhuang coal mine. field data, (ii) finding operation, and (iii) location-based information operation. For example, the maximum methane concentration with its coordinates in an area of interest will be demonstrated immediately by the function of polygonal query, which also shows whether the predicted concentration exceeds the threshold value, as can be seen in Figure 9.  
Besides, if a specific point is of interest in an actual field, for example, the position is where miners always work, then the point can be clicked or the coordinate can be input on the interface  
Figure 8: Methane concentration integrated with various spatial coal mine layers. Figure 9: Methane concentration visualization and polygonal query analysis. to get the methane concentration curve changed over time, which will be displayed on the interface and provides intuitive information for the dynamic regularity of methane concentration. The time series data can also be validated with monitored data based on the database management system.