Summary
In the fire safety design of parking lots and buildings, estimating the possibility of fire spreading to surrounding combustibles, such as neighboring buildings and cars, is essential. The ignition possibility to surrounding combustibles can be predicted from the heat flux from a burning car to the combustibles. In this study, we conducted 2 full‐scale car fire experiments using minivan passenger cars and measured the heat fluxes to their surroundings. The cars were ignited at the rear bumper with 80 g of alcohol gel fuel. The windows were closed. Heat flux gauges were placed around the car to measure the heat flux in various directions. Cedar boards were placed next to the gauges, and burn damage to the boards was observed. When the windows shattered in succession, combustion in the passenger compartment became larger. At a distance of 50 cm from the burning car, the heat flux was greater than 40 kW/m2, and most of the cedar boards were completely burned. At a distance of 1 m, the heat flux was 10 to 20 kW/m2, and some of the cedar boards were burned. We devised a method for modeling the shape and temperature of flames in the burning cars. Furthermore, we propose a method for calculating heat fluxes in the lateral direction of the burning minivan passenger car, and we compared the calculated and measured heat fluxes as a means of verifying the proposed method. The shape of flame in the burning car was approximated as a rectangular prism to calculate the heat flux. The calculation results were in good agreement with the experimental results. The proposed method is expected to be useful for fire safety engineering.
SUMMARYRate control for multicasting is required for multipoint distribution of video over the Internet. In this paper, we focus on the video image quality during playback and propose layered multicast rate control using error correcting codes. First, we identify the severe degradation problem in the playback quality of the transmitted video due to packet losses resulting from congestion when transmitting high-quality video using conventional techniques. To address this problem, we propose a method adopting the parity generated by the error correcting code in addition to the rate control in order to maintain the video image quality. We perform a simulation to show that the proposed method enables rate control that prevents the degradation in quality caused by congestion. Furthermore, we find the optimum block size of the error correcting code with respect to the control latency, and quantitatively evaluate the packet loss ratio and transmission efficiency with respect to the system scale and the transmission efficiency with respect to the layer increment ratio. We also develop a layer coding technique and study the optimum error correcting code in real-time processing by the software and its implementability.
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