Site Selection of Fire Stations in Large Cities Based on Actual Spatiotemporal Demands: A Case Study of Nanjing City

The rapid expansion of cities brings in new challenges for the urban firefighting security, while the increasing fire frequency poses serious threats to the life, property, and safety of individuals living in cities. Firefighting in cities is a challenging task, and the optimal spatial arrangement of fire stations is critical to firefighting security. However, existing researches lack any consideration of the negative effects of the spatial randomness of fire outbreaks and delayed response time due to traffic jams upon the site selection. Based on the set cover location model integrated with the spatiotemporal big data, this paper combines the fire outbreak point with the traffic situation. The presented site selection strategy manages to ensure the arrival of the firefighting task force at random simulated fire outbreak points within the required time, under the constraints of the actual city planning and traffic situation. Taking Nanjing city as an example, this paper collects multi-source big data for the comprehensive analysis, including the full data of the fire outbreak history from June 2014 to June 2018, the traffic jam data based on the Amap, and the investigation data of the firefighting facilities in Nanjing. The regularity behind fire outbreaks is analyzed, the factors related to fire risks are identified, and the risk score is calculated. The previous fire outbreak points are put through the clustering analysis, the spatial distribution probability at points in each cluster is calculated according to the clustering score, and the random fire outbreak points are generated via the Monte Carlo simulation. Meanwhile, the objective emergency response time is set as five minutes. The average vehicle speed for each road in the urban area is calculated, and the actual traffic network model is built to compute the travel time from massive randomly-distributed simulated fire points. The problem is solved by making the travel time for all simulated demand points below five minutes. At last, the site selection result based on our model is adjusted and validated, according to the planned land use. The presented method incorporates the view of the spatiotemporal big data and provides a new idea and technical method for the modification and efficiency improvement of the fire station site selection model, contributing to a service cover ratio increase from 58% to 90%.

Development and validation of simple-shield thermocouple in fire environments

A novel simple-shield thermocouple that is capable of radiation correction in fire environments and that has a simpler structure and greater convenience than conventional aspirated thermocouples was proposed. The measurement errors of bare-bead, double-shield aspirated, and simple-shield thermocouples were then compared in a simulated fire environment. In addition, a fire experiment using wood cribs was performed in order to verify the measurement performance of the proposed simple-shield thermocouple in a real fire environment using a one-third-scale ISO 9705 room. The simple-shield thermocouple produced fairly accurate temperatures that fell within 5% of the actual gas temperature in the simulated fire environment. In addition, variations in the surface emissivity and the installation angle of the simple-shield thermocouple in the real fire environment further reduced the measurement error. With a radiant heat flux of 20 kW/m2, it was confirmed that the bare-bead thermocouple had a relative measurement error of up to 80% compared to the aspirated thermocouple, while the proposed simple-shield thermocouple was capable of measuring the temperature within a relative error of around 15% compared to the aspirated thermocouple.

Effect of Different Matrices on the Identification of Ignitable Liquid Residue in Post Burn Arson Debris: A Multi-Derivative UV-Visible Spectrophotometric Approach

Analysis of arson debris is the foremost challenging task to the forensic investigators. Identification of the ignitable liquid residues in the fire debris is one of the prime objectives of forensic quest. This study evaluates the potential of derivative ultraviolet-visible spectrophotometric methods for the analysis and identification of ignitable liquid residues. In this work, arson was simulated using kerosene as an ignitable liquid on various matrices. Derivative UV spectra of kerosene were recorded in their neat state and compared with those obtained from simulated fire debris samples for the identification and detection of ignitable liquid residues. It was observed that different burnt substrates did not cause any interference. The obtained results indicated that the ignitable liquid absorption capacity of the substrate can play an important role in the extraction and identification of ignitable liquid from fire debris. The used technique proved to be rapid, easy, reproducible and efficient.