Bayesian Inference of Fire Evolution Within a Compartment Using Heat Flux Measurements

The dynamical evolution of a multiple fuel package fire leaves thermal signatures. For practical and theoretical reasons, it is important to determine conditions in which one can identify the path the system took by conducting a set of experiments that cover the space of all possible paths. An experimental fire compartment capable of producing repeatable and highly customizable fire-evolution scenarios is presented. Instrumented propane burners are configured in the compartment each with a simple critical heat flux ignition model. Heat flux sensors are located around the burner configuration to provide temporal incident heat flux measurements. Data from several hypotheses representing possible scenarios are compared to data generated using some true configuration using a Bayesian methodology. The Bayesian methodology is able to illicit the correct fire-evolution scenario from the set of hypotheses with a high degree of confidence. The information content provided by each sensor is analyzed to highlight the importance of sensor location in determining the fire-evolution. Posteriors for the hypotheses using two different error structures are also compared over the sensors to highlight the importance of choosing the correct error structure.

     

Probabilistic Fire Simulation Assessment Using Simplified Model and Zone Modelling of a Kitchen Fire Scenario

Fire Technology - Probabilistic fire simulation has been gaining interest in performance-based design approach. Very few evaluations on modelling performance can lead to...     

Intelligent Space as a Framework for Fire Detection and Evacuation

This article discusses the application of Intelligent Space (iSpace) for fire related purposes. Both fire detection and fire evacuation are studied. It is shown that iSpace can improve current fire detection algorithms and offers a situation adaptable fire evacuation at the same time. As in future more and more factories and homes are expected to be of the iSpace concept, fire related application of iSpace is simply an addition of appropriate software and is therefore extremely easy and inexpensive.     

Measuring Radiation Heat Fluxes from a Jet Fire Using a Lumped Capacitance Model

This paper presents an experimental methodology for measuring the incident radiation heat flux distribution surrounding a jet fire. The methodology uses a line of surface thermocouples attached to a steel bar. The thermocouples measure the temperature time history of the steel bar in response to an imposed incident radiation heat flux. The theoretical basis of the methodology is an energy balance for any point on the steel bar. The energy balance is formulated as a lumped capacitance model. All of the assumptions in the theory are shown to be valid and the accuracy of the experimental methodology demonstrated.     

Random Process Model for Urban Traffic Flow Using a Wavelet‐Bayesian Hierarchical Technique

Abstract: The existing well‐known short‐term traffic forecasting algorithms require large traffic flow data sets, including information on current traffic scenarios to predict the future traffic conditions. This article proposes a random process traffic volume model that enables estimation and prediction of traffic volume at sites where such large and continuous data sets of traffic condition related information are unavailable. The proposed model is based on a combination of wavelet analysis (WA) and Bayesian hierarchical methodology (BHM). The average daily “trend” of urban traffic flow observations can be reliably modeled using discrete WA. The remaining fluctuating parts of the traffic volume observations are modeled using BHM. This BHM modeling considers that the variance of the urban traffic flow observations from an intersection vary with the time‐of‐the‐day. A case study has been performed at two busy junctions at the city‐centre of Dublin to validate the effectiveness of the strategy.     

消防应急照明和疏散指示系统应注意问题探讨

从消防应急照明的设计依据、供配电与电源切换、灯具启动、蓄电池持续供电时间、集中电源和应急照明配电箱配电容量和范围、特低电压照明装置供电安全等方面探讨消防应急照明应关注的问题.     

Measuring Water Flow Rate for a Fire Hose Using a Wireless Sensor Network for Smart Fire Fighting

Fire Technology - A wireless sensor network was created to measure water-flow rate in a fire hose. An integrated electronic piezoelectric accelerometer was chosen as the sensor to measure the flow...     

浅析某广场的消防系统改造设计

本文针对某消防系统的改造工程进行了阐述，重点分析了该工程前期所存在的主要问题，并基于这些问题提出了具体的改造设计方案。     

浅论火场逃生

近年来,一场火灾烧死数十人、数百人的 惨剧屡见不鲜,在火灾降临后如何防止和减少人员伤亡,是值得关注的问题。本文着重介绍火灾发展的规律及火场上致人伤亡的因素,分析人在火灾中的表现行为,提出火场逃生的准备、原则和注意事项并详细介绍了十种火场逃生的方法。     

数字孪生技术在建筑火灾安全评估与改造中的应用研究

数字孪生技术可建立现实对象与数字模型的精确对应关系, 进而开展基于真实数据的仿真, 以指导现实对象改进。以北京科技大学土木楼为例, 开展了基于数字孪生架构的建筑火灾安全评估与改造的研究。首先, 利用建筑信息建模(BIM)、物联网（IoT）和云技术(cloud technology), 并集成了风速、人数等实时感知数据, 建立了土木楼的数字孪生模型; 其次, 利用数字孪生模型, 开展基于实测数据的火灾蔓延与人员疏散模拟, 并与基于传统估计数据的模拟结果进行了比较; 最后, 根据模拟结果, 提出了建筑火灾安全的改进方案, 并评测了改进方案的效果, 为建筑消防安全改造提供了准确依据。结果表明: 数字孪生架构下的火灾安全评估结果更接近实际, 可以指导建筑火灾安全改造。     

Predicting the Fire Dynamics of Exposed Timber Surfaces in Compartments Using a Two-Zone Model

There is an increasing desire to use more engineered timber products in buildings, due to the perceived aesthetics of timber and desire for more sustainable architecture. However, there are concerns about fire performance of these products especially in taller buildings. This has led to renewed research to understand the behaviour of timber surfaces in compartments exposed to fire. This paper describes a two-zone calculation model for determining the fire environment within a compartment constructed from timber products where varying amounts of timber are exposed on the walls and ceiling. A set of eight full-scale compartment experiments previously reported in the literature are used to assess the capability of the model. The fire load energy density in the experiments ranged from 92 MJ/m² to 366 MJ/m² comprising either wood cribs or bedroom furniture with the largest compartment having dimensions 4.5?×?3.5?×?2.5 m high with an opening 1.069 m wide?×?2.0 m high. The experiments were ventilation-controlled. It is shown that the model can be used to provide conservative predictions of the fire temperatures for compartments with timber exposed on the walls and/or ceiling as part of an engineering analysis. There are several limitations that are discussed including the need to consider the debonding of layers in the case of cross-laminated timber. It is recommended that further benchmarking of the model be done for different ventilation conditions and with engineered timber products where debonding does not occur. This will test the model under a wider range of conditions than examined in this paper.     

A Probabilistic Framework for Bayesian Adaptive Forecasting of Project Progress

Abstract:   A methodology to forecast project progress and final time-to-completion is developed. An adaptive Bayesian updating method is used to assess the unknown model parameters based on recorded data and pertinent prior information. Recorded data can include equality, upper bound, and lower bound data. The proposed approach properly accounts for all the prevailing uncertainties, including model errors arising from an inaccurate model form or missing variables, measurement errors, statistical uncertainty, and volitional uncertainty .
As an illustration of the proposed approach, the project progress and final time-to-completion of an example project are forecasted. For this illustration construction of civilian nuclear power plants in the United States is considered. This application considers two cases (1) no information is available prior to observing the actual progress data of a specified plant and (2) the construction progress of eight other nuclear power plants is available. The example shows that an informative prior is important to make accurate predictions when only a few records are available. This is also the time when forecasts are most valuable to the project manager. Having or not having prior information does not have any practical effect on the forecast when progress on a significant portion of the project has been recorded .     

应急照明消防强启控制在施工中应注意的问题

针对工程建设项目中,应急照明的消防强启控制原理及其接线存在的一些问题进行探讨,并指出建筑电气施工中容易出错的地方和应注意的问题。     

火灾中端板连接件的屈服线模型的研究进展

特定温度下连接件的设计一般只考虑初始刚度和塑性抗力,然而结构在高温作用下发生大变形时其延性和破坏模式就显得更为重要。本文通过对T型连接模型的分析得到大变形,包括发生破坏的部位处端板连接件的性能。基于虚功原理建立的该模型,能很容易地应用于端板连接,而且能考虑到T型连接的翼缘和螺栓同时屈服后的材料硬化。同时还包括对这两个构件相容性的分析。对常温和升温环境中T型连接试验的验证表明:提出的模型可以预测T型连接的多种性能特征。通过与有限元分析结果对比发现:该模型可以很好地反映端板连接的性能。     

A Framework for Risk-Informed Performance-Based Fire Protection Design for the Built Environment

Performance-based fire protection design (PBFPD) approaches have now been in use for more than 20 years. One might be tempted to conclude that the current ‘state of the art’ is working well. However, application of PBFPD remains limited, several shortcomings exist, and an increasing number of countries are moving toward ‘prescribed performance’ to address the gaps. There are many factors contributing to these problems with PBFPD. Research has been carried out in two principal problem areas: the relationship between occupants and fire safety measures in the context of holistic building performance expectations during everyday use of the building, and also the lack of specifics within current PBFPD approaches. To address these concerns, a new framework for risk-informed PBFPD has been developed, centered on the study of systems formed by specific building types and their associated occupants. This framework replaces generic guidance with a more in-depth and targeted “building-occupant” system approach. This article focuses on how a successful implementation of the new risk-informed PBFPD approach will require acceptance of the need for a paradigm shift from one in which fire is the center of the problem to one in which building performance metrics are evaluated in case of fire events. This article also details the different steps of the new PBFPD process and how this process differs from the current ones, notably in separating technical steps from political steps related to decision making and policy. Finally, this article presents how the new approach is practically applied to a project, focusing on a proof of concept of the new PBFPD process.     

A Study of Total Flooding Water Mist Fire Suppression System Performance Using a Transient One-Zone Computer Model

Due to the intense R&D activity in the field of water mist fire suppression during the past decade, the qualitative and quantitative understanding on the performance of water mist has increased significantly. This development has led to a point in which quantitative theoretical models describing large-scale water mist fire suppression systems begin to emerge. This paper describes the composition and validation of one such model, designed for total flooding water mist applications, especially against flammable liquid hazards in enclosures. The basic construction of the model is first described, followed by an example on the validation of the model using full-scale experimental data. The model is then used to investigate the limitations to the maximum possible mist concentration in the protected space. The potential of the model as an engineering tool is illustrated by making predictions on the scaling laws associated with water mist systems in the framework of IMO MSC/Circ.668/728 as the enclosure volumes and ventilation conditions are varied. The predictions are found to be in agreement with what is indicated by the recent US Coast Guard test series in very large machinery spaces.