Heat loss to the ground from a building—II. Slab on the ground

The heat flow to the ground from a rectangular slab with an even thermal insulation is analysed. The steady-state heat loss factor is given in complete diagrams for any ratio between length and width of the slab and for any constant insulation of slab and ground surface. A two-dimensional edge approximation for time-dependent heat loss at the perimeter of the slab is introduced. New analytical solutions for the edge heat loss due to periodically variable outdoor temperature or a step change in the outdoor temperature are presented. The effect on the heat loss due to different variations of the outdoor temperature is easily analyzed with these solutions. For example, daily periodic variations can certainly be neglected. Based on this, simple design rules for the heat loss during a heating season and the peak effect are given.     

Artificial lighting in classrooms—results of a lighting survey

This paper summarises the results of a survey to determine the provision of artificial lighting in 59 classrooms. The rooms are sited in five different teaching institutions. Details of the survey equipment, and the methods of illuminance and luminance measurement are described. The measured values show that a wide variation exists between rooms.

The results of the survey are compared to the illuminance and glare recommendations in three different artificial lighting design codes. Many of the classrooms fail to meet the minimum requirements of these guides. A need for further work to establish the causes of these deficiencies is identified.     

The analysis of some practical methods for limit state verification in coupled instability—comparison with the experimental evidence

The paper analyzes the concept of evaluation by calculus of the stability limit state for members subjected to combined bending and axial compression.

The calculus procedure stipulated in Eurocode 3, Design of Steel Structures, 1990¹ is presented for the case in which flexural-torsional buckling is a potential failure mode (compression and bending about the major axis of the section).

The verification function, stipulated in the Eurocode is analyzed by comparison with some experimental results.

The analysis is one of the Steel Structures Department's (Civil Engineering Institute, Bucharest) concerns regarding the improvement of Romanian Code STAS 10108/0–78 ‘Metal Structures’.     

Calculating fire plume characteristics in a two-layer environment

Methods are developed to determine axial gas flow conditions within a weakly buoyant plume that passes from an ambient quiescent environment, in which the plume originates, to an upper layer at elevated temperatures. The methods are appropriate for inclusion in two-layer analysis of enclosure fire. In particular, they are first steps in developing a prediction of actuation time for thermally activated automatic sprinklers exposed to an enclosure fire. Results obtained with various methods are compared with measurements in a 1.22 m diameter cylindrical enclosure. National Bureau of Standards Reference: David D. Evans, “Calculating Fire Plume Characteristics in a Two Layer Environment”, Fire Technology, Vol. 20, No. 3, August 1984, p. 39. Note: This paper is a contribution of the National Bureau of Standards and is not subject to copyright.     

The development of epigeic fauna in new hedges — a comparison of spatial and temporal trends

The colonisation of a linear sequence of nine young hedge plantations (each 400 m²) within an intensely cultivated landscape about 30 km to the west of Bonn has been studied to compare spatial and temporal distribution patterns of epigeic arthropods in order to consider differences obtained concerning an assessment of colonisation characteristics and dispersal trends. The investigation was started in 1982, the year in which the new hedges were planted and continued until 1991. Pitfall traps—usually six as a standard set—were installed in young hedges and in old wooded habitats of an adjacent semi-natural habitat complex, as well as in surrounding arable fields and in meadow strips connecting the hedge plantations. But only in 1990 nearly all the habitats were sampled at the same time. Between 1982 and 1989 catches were continuously performed only in two habitats, since 1986 in four young habitats.Results on species of the taxonomical groups of Carabidae, Opilionida and Araneida show that the analysis of spatial only or temporal only patterns can lead to different interpretations and sometimes wrong conclusions about the colonisation of new hedge habitats. Both types of data, comprehensive spatial and long-term temporal, are complementary and a combination of both is recommended for properly assessing dispersal of species and other dynamic processes in the landscape. As far as the colonisation of new hedges is concerned it is shown that despite high temporal dynamics in species abundances and remarkable differences between the three taxa considered, the development towards a typical hedge fauna progresses very slowly. Small, 9-year-old hedges do not function well as stepping stones for the dispersal of epigeic forest and forest-edge arthropods, and only a small corridor effect could be established for the linear plantation strip. Remarkable differences in colonisation trends between beetle and spider species of similar ecological preferences are discussed.     

Recent developments and applications in structural fire engineering design—A review

This review outlines some of the major developments that have occurred in structural fire engineering design during recent years.

The general principles used in fire engineering are discussed together with the various approaches that can be adopted by an architect or engineer to design a structure capable of withstanding the attack of fire without collapsing, using scientific concepts as a basis for determining the fire resistance and protection requirements. Details are provided of recent full-scale tests and research work either completed or in hand with the aim of producing design concepts and information which the fire engineer may use. Examples are discussed to show how structural fire engineering has been utilised in both large and small buildings to precisely define the fire resistance and protection requirements of steel frameworks. In some instances, estimates of the financial savings realised in following this type of approach are also given.     

An experimental study on the effect of ventilation velocity on burning rate in tunnel fires—heptane pool fire case

The 1/20 reduced-scale experiments using Froude scaling are conducted to investigate the effect of longitudinal ventilation velocity on the burning rate in tunnel fires. The n-heptane pool fires with heat release rate ranging from 3.71 to 15.6 kW are used in this study. A load cell is used to measure the mass loss rate of burning fuel and the temperature distributions are measured by K-type thermocouples in order to investigate smoke movement. The ventilation velocity in the reduced-scale tunnel is controlled by the wind tunnel through an inverter. The increases in ventilation velocity lead to enhance burning rate of n-heptane fuel. The reason is that the oxygen supply effect prevails rather than the cooling effect as the ventilation velocity increases. As a result, the heat release rates in experiment are larger than constant heat release rates by 4.45–11.3 times in the n-heptane pool fires. Also, it is found that non-dimensional critical ventilation velocity is proportional to one-third power of non-dimensional heat release rate.     

火灾现场勘查中环境勘查的方法和策略研究

对火灾现场勘查中环境勘查的重要性进行了阐述 ,并对其方法及策略进行了总结和研究。     

Evaluation of deterministic fire models: Part I— Introduction

During 1989 and 1990, a preliminary evaluation of four deterministic fire models was carried out by the University of Edinburgh at the request of the Home Office (London). This paper is the first in a series based on this work and contains material common to the entire study. The models considered were ASET, HAZARD1, FIRST and JASMINE.     

Bayesian estimation of occupancy distribution in a multi-room office building based on CO<Subscript>2</Subscript> concentrations

Occupancy information in an office building is an important asset for determining energy-efficient operations and emergency evacuation of a building. In this study, we developed a method to estimate the occupancy distribution in a multi-room office building using Bayesian inference. The Markov chain Monte Carlo algorithm was used to estimate the real-time occupancy in individual rooms based on indoor carbon dioxide concentrations. The office building was made-up of five rooms with different physical configurations and dimensions, and the rooms were air-conditioned and ventilated by a central air handling unit. The carbon dioxide concentration data were generated by the simulation software CONTAMW according to a given schedule of occupancy and the supply airflow rates in each room. The objective of the present paper is to investigate the effects of various parameters of Bayesian inference on the accuracy of estimation results. The parameters include the probability of prior information, the uncertainty level of CO₂ data, and the time interval for monitoring CO₂.     

The collapse of welded aluminium plate girders—an experimental study

Twenty-two tests conducted to study the collapse behaviour of welded aluminium girders are described. The girders are of varying proportions, have transverse or longitudinal web stiffeners and are subjected to different combinations of shear and bending loads. It is observed that, although shear sway mechanisms similar to those for steel girders do develop, the webs of aluminium girders may fracture in the heat affected zones adjacent to the perimeter welds. These fractures develop at some stage during the formation of the collapse mechanism and are the consequence, rather than the cause, of failure. It is shown that the tension field theory, originally developed for steel girders, may overestimate the shear-carrying capacity of aluminium girders and it is concluded that the theory requires some modification before it can be applied with confidence to aluminium girders.     

火灾对环境的影响及对策

火灾时产生的浓烟及其有毒气体直接或间接地影响着环境,如何预防和减少火灾对于环境的污染成为最大限度地降低火灾危害的重要课题,分析了燃烧产物对环境的影响,提出了保护环境的安全对策.     

Laterally supported sandwich panels subjected to large deflections—Part 1: Test apparatus design and experimental results

This paper deals with the experimental characterization of the structural behavior of sandwich panels under distributed transverse loadings. A configuration typically used in aircraft interior applications is considered: a simply supported rectangular plate fixed by bolts on the two longitudinal edges or on all four edges. The panel and joint stiffness are experimentally evaluated and a test apparatus is designed and instrumented to measure the reaction shear loads at the panel attachment bolts and the transverse deflection of the plate. The results demonstrate the importance of a nonlinear analysis for the design of this type of structure. A companion paper, describes the FE analysis procedure utilized to simulate the nonlinear behavior of the tested panels. The numerical results are validated against the experimental results.     

Activated sludge pilot plant: comparison between experimental and predicted concentration profiles using three different modelling approaches

This paper presents an experimental and numerical study of an activated sludge channel pilot plant. Concentration profiles of oxygen, COD, NO₃ and NH₄ have been measured for several operating conditions. These profiles have been compared to the simulated ones with three different modelling approaches, namely a systemic approach, CFD and compartmental modelling. For these three approaches, the kinetics model was the ASM-1 model (Henze et al., 2001). The three approaches allowed a reasonable simulation of all the concentration profiles except for ammonium for which the simulations results were far from the experimental ones. The analysis of the results showed that the role of the kinetics model is of primary importance for the prediction of activated sludge reactors performance. The fact that existing kinetics parameters in the literature have been determined by parametric optimisation using a systemic model limits the reliability of the prediction of local concentrations and of the local design of activated sludge reactors.     

Drag pick cutting tests: A comparison between experimental and theoretical results

This paper aims at reporting the results of a number of drag pick cutting tests on selected igneous rock samples to compare the experimentally determined maximum cutting force (FC^′) values with theoretically estimated ones. First, a review on theoretical rock cutting models proposed for both chisel and conical picks was presented in detail. Experimental study consists of both chisel and conical pick cutting tests in unrelieved (single-pick) cutting mode with varying cutting depths. FC^′ values were determined from experimental results, and theoretical models were utilized to compute FC^′ for all cutting conditions. Computed and experimentally determined FC^′ data were then compared for a referenced cutting depth. It is shown that the theoretical models might overestimate or underestimate FC^′ and cannot give reliable results. Finally, explanations for these mismatches were presented.     

Face layer wrinkling in sandwich shells— theoretical and experimental investigations

Wrinkling of the face layers is one of the typical failure modes in sandwich structures. Different aspects of this phenomenon are investigated in this paper: analytical considerations concern the determination of wrinkling loads for anisotropic elastic sandwiches under uniaxial as well as biaxial loading. Finite element calculations are carried out to investigate the postbuckling behaviour of isotropic sandwiches, with different combinations of nonlinear material combinations, under compressive and/or bending loading, and experimental studies are performed to verify the analytical and numerical results, respectively.     

磷酸铵盐干粉灭火剂灭火性能的计算比较

阐述了磷酸铵盐干粉灭火剂灭火性能的计算比较方法。干粉灭火剂的灭火过程可用两个重要参数表征 ,即最大灭火效能和小粒子 (<38μm)的最佳比。在粒度分布的基础上 ,通过计算上述两个重要参数 ,相互比较 ,可初步了解它们的灭火性能 ,及时监测产品质量。     

消防产业的可持续发展与环境保护

分析了消防产业可持续发展与环境保护之间存在的密不可分的紧密关系 ,指出了我国消防产业的发展现状和存在的问题 ,重点介绍国外在消防产业可持续发展和环境保护方面所开展的研究和所采取的技术措施 ,提出了我国消防产业可持续发展与环境保护应采取和强化的技术措施和对策