Screens surrounding openings in floor slabs of public buildings

Introduction. Screens often surround openings in the floor slabs of atrium buildings to prevent the spread of fire hazards to higher floors and to improve the efficiency of smoke ventilation systems. In this article, the co-authors assess the expediency of installing screens around openings in the floor slabs and identify the best screen height values. In this article, the co-authors perform a quantitative analysis of the ability of screens to prevent the propagation of hazardous fire factors, to identify general regularities typical for a multi-level space, and to develop recommendations for the installation of screens inside public buildings. The co-authors suggest that screen height should be a solution to the following tradeoff problem: the use of screens reduces acceptable evacuation time for the floor that has screens installed and rises the evacuation time for higher floors.Rational screen height selection algorithm. The co-authors propose the following algorithm for the two-stage selection of the rational screen height. At the first stage, the evacuation problem is resolved. As a result, evacuation completion time is determined for emergency exits. Further, acceptable evacuation time and the time needed to block emergency floor exits are identified for a particular type of a fire alarm system.At the second stage, the dynamics of hazardous fire factors in building rooms is assessed for various screen heights. As a result, the rational height of screens is established for the evacuation time to remain positive.Conclusions. Screen height values cannot be determined in advance. Each case requires an individual approach that entails the resolution of evacuation problems and the tracking of the dynamics of hazardous fire factors in buildings that have multi-height spaces. These ideas are in line with the concept of flexible regulation of fire protection systems designated for construction facilities.

Video bit-rate requirements for 8K 120-Hz HEVC/H.265 temporal scalable coding: experimental study based on 8K subjective evaluations

8K video parameters were designed to provide an immersive experience; meanwhile, special considerations are necessary to assess the entire screen subjectively. This paper studies the video bit-rate required for 8K 119.88-Hz (120-Hz) and 59.94-Hz (60-Hz) the high efficiency video coding (HEVC)/H.265 temporal scalable coding based on subjective evaluation experiments. To investigate the appropriate bit-rate for both 8K 120- and 60-Hz videos for broadcasting purposes, we compress 8K 120-Hz test sequences using software that emulates our real-time HEVC encoder and conduct two types of experiments. The experimental results demonstrate that the required video bit-rate for 8K 120-Hz temporal scalable coding is estimated to be 85–110 Mbps, which is equivalent to the practical bit-rate for 8K 60-Hz videos, and the appropriate bit-rate for 8K 60-Hz video in 8K 120-Hz video at 85 Mbps is assumed to be ~80 Mbps. From the analyses of the encoded videos, it is confirmed that the experimental results are primarily influenced by the image quality on the slice boundary positioned at the middle of the screen height. When conducting the experiments, we determined settings referring to an initial 8K subjective assessment; we further mention requirements for future 8K subjective evaluations from the experimental results.

Influence of the ground on the sound screen efficiency

Characteristic features of evaluating the acoustic efficiency of sound screen on the ground were considered. To simplify the analysis, noise source and control point were located symmetrically on both sides of the screen. Their position was determined by the angle α and by the effective screen height. Influence of the α on the efficiency of a semi-infinite screen, and then on a decrease in this efficiency in the presence of the ground was analyzed.