Numerical study on the effect of shaft position on natural smoke exhaust in tunnels with one closed portal

.This paper uses Fire Dynamics Simulator (FDS) to study the effect of the longitudinal distance from the shaft to the fire source on the natural smoke exhaust of the tunnel fire with one closed portal, and analyzes the temperature distribution of the smoke and the shaft’s smoke exhaust efficiency. The results show that when the shaft is located downstream of the fire source (Ds0), the smoke exhaust efficiency increases slightly with the increase of the distance from the shaft to the fire source, but the overall value is relatively small. When HRR is fixed, the shaft located downstream of the fire source has a higher smoke exhaust efficiency. As the distance between the shaft and the fire source increases, the plug phenomenon decreases

Research and Exploration on Ideological and Political Theories Teaching in the Course of Soil Science Experiment: Taking Pingdingshan University as an Example

Experimental course is an important link of ideological and political education in colleges and universities under the new situation,and plays an important role in the construction of ideological and political theories teaching in the course.Taking Pingdingshan University as an example,by introducing the real soil cases in Pingdingshan area,the ideological and political elements of the course are integrated into the teaching links of laboratory safety training,self-study before class,experimental teaching implementation,evaluation and improvement.By implementing the concept of "All-round Education" in experimental teaching,we are committed to realizing the comprehensive coverage of value shaping,knowledge inheritance and ability training,and explore and practice the reform of ideological and political theories teaching in the course of Soil Science Experiment

The effect of blockage and tunnel slope on smoke spread and ceiling temperature distribution in a natural-ventilated metro depot

The current research investigated the coupling effect of blockage and tunnel slope on spreading characteristics of the fire smoke and ceiling temperature distribution in a metro depot with one closed end. A series of 1/15 reduced scale experiments and full-scale numerical simulations were conducted to capture the global fire characteristics. The investigation addressed and compared the effect of tunnel slope on the fire plume behavior and ceiling temperature distribution in both uphill and downhill situations. The presence of the blockage upstream of the fire was further investigated to highlight the heat accumulation between the closed end and fire, and the associated effect on the pool fire mass burning rate. Comparison has been made between the ceiling temperature distribution of when the tunnel slope increases in both uphill and downhill tunnels. The coupling effect of blockage and tunnel slope was analyzed in relation to the maximum and extent of high temperature area at tunnel ceiling. Two empirical correlations have also been proposed to predict the maximum temperature and upstream temperature attenuation in a metro depot, accounting for the influence of blockage and tunnel slope. Comparison among the measurements, predicted values, literature models and data exhibit relatively good agreement

Construction Method of Ideological and Political Theories Teaching in the Course of Environmental Microbiology for Environmental and Ecological Engineering Major

Environmental Microbiology is a professional basic course in the curriculum system of Environmental and Ecological Engineering major,which follows the requirements of ideological and political theories teaching in the course in higher education,and should be implemented in every course.Therefore,the construction of ideological and political theories teaching in the course should be an important task in the course construction of Environmental Microbiology.In view of the curriculum characteristics of Environmental Microbiology,such as multi-disciplinary feature,wide coverage and rapid development,it is an effective method for the construction of ideological and political theories teaching in the course of Environmental Microbiology by fully tapping the ideological and political elements of the curriculum,such as patriotism,scientific spirit and practical innovation,and integrating the ideological and political theories teaching in the course into the whole curriculum design and classroom teaching construction

Construction Method of Ideological and Political Theories Teaching in the Course of Environmental Microbiology for Environmental and Ecological Engineering Major

Environmental Microbiology is a professional basic course in the curriculum system of Environmental and Ecological Engineering major,which follows the requirements of ideological and political theories teaching in the course in higher education,and should be implemented in every course.Therefore,the construction of ideological and political theories teaching in the course should be an important task in the course construction of Environmental Microbiology.In view of the curriculum characteristics of Environmental Microbiology,such as multi-disciplinary feature,wide coverage and rapid development,it is an effective method for the construction of ideological and political theories teaching in the course of Environmental Microbiology by fully tapping the ideological and political elements of the curriculum,such as patriotism,scientific spirit and practical innovation,and integrating the ideological and political theories teaching in the course into the whole curriculum design and classroom teaching construction

Effect of ceiling extraction on the smoke spreading characteristics and temperature profiles in a tunnel with one closed end

A series of fire tests in a 1/15 scaled-model tunnel with one closed end have been conducted. Analysis was carried out to explore temperature distribution and smoke propagation under the influence of ceiling extraction system. Five different heat release rates, three dimensions of exhaust outlet, and numerous extraction rates were considered. Experimental results led to some interesting findings about the relationships between smoke extraction rate, fuel mass burning rate, and ceiling temperature. Two distinctive ceiling temperature regions were identified according to their different responses to smoke extraction rate, i.e., ceiling temperature decay between the fire and outlet was almost independent of smoke extraction rate while temperature upstream of the outlet decreased sharply with the increase of smoke extraction rate. Analysis was also conducted about smoke back-layering length, revealing its strong dependence on heat release rate and induced air velocity. Based on the experimental results and dimensional analysis, three empirical formulas were proposed to capture ceiling temperature decay and smoke back-layering length for tunnels with one closed end utilizing ceiling smoke extraction