Burning Rate of Liquid Fuel on Carpet (Porous Media)

The occurrence of a liquid fuel burning on carpet has been involved in many incendiary and accidental fires. While the research on a liquid fuel fire on carpet is still limited, much work on porous media has been performed using sand or glass beads soaked with liquid fuel. In this study, a heat and mass transfer theory was first developed to analyze the burning process of liquid on carpet, and then several small-scale tests were performed to validate the theory. This analysis is valid for pool fires intermediate in size (5–20 cm. in diameter). The experimental apparatus consisted of a circular pan (105 mm) and a load cell. Varying amounts of fuels (heptane, kerosene and methanol) were spilled onto the carpet, which was allowed to burn in a quiescent environment. It was found that due to the different controlling mechanisms, the liquid burning rate could be less or more than that of a similarly spilled free-burning pool fire. For the worst-case scenario in fires, the maximum enhancement of the burning rate due to the porous media is predictable through the physical properties of the fuel. This analysis is valid for both combustion and evaporation. Several similar results in the scientific literature are analyzed to further describe the trend. This work explains the role of carpet in liquid pool fires and also helps to explain special risks related to the presence of carpet involved in arsons and will be useful in reconstruction of the early development of an incendiary or accidental fire.     

UASB反应器在垃圾渗滤液处理中的应用

介绍了垃圾渗滤液的特点、水质的影响因素、处理方法以及UASB反应器的组成、工作原理和特点等,结合工程实例,论述了垃圾渗滤液工艺流程的确定,混凝土构筑物施工以及UASB反应器处理单元的启动调试工作。     

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.     

液态金属快堆主管道中超声导波传播特性研究

讨论了钠冷快堆(Sodium-cooled Fast Reactor,SFR)主管道的整体温度和内部液态金属钠流动速度的变化对管道导波传播特性的影响。推导了充液管道中导波频散方程的一般形式,并给出了管道内液态金属钠处于流动状态下的导波频散方程。采用数值计算方法获得了管内液态金属钠处于不同温度和不同流速时的导波纵向模式频散曲线和导波时域波形。结果表明,温度变化对基阶纵向模式的影响较小,但对高阶纵向模式的影响较大;液态钠流速增大会使导波频散曲线向高频轻微移动,但在实际检测中可以忽路管内液体流动速度的影响。通过对时域接收波形的模拟计算,进一步考察了液态金属钠的温度及流动速度变化对导波传播的影响,并通过对比不同模态的激发特点和不同频段的导波时域波形特点,结合导波频散曲线,给出了适用于SFR管道超声无损检测的导波模态和声源激发频段选择方案。     

An Assessment of Water Demand Management Options from a Systems Approach

A systems approach is used to model the urban water and wastewater system. Scenarios are developed for the implementation of a range of water demand management measures, including (a) leakage reduction, (b) the increasing use of water metering, (c) the replacement of standard WCs by low-flow WCs, and (d) the introduction of greywater recycling systems. These measures are assessed according to the water saving, cost per unit of water saved, and other indicators of the relative contribution to the sustainability of the system. Preliminary assessments of selected environmental costs and benefits are also included.     

Assessment of the solubility and bioaccessibility of arsenic in realgar wine using a simulated gastrointestinal system

Consumption of arsenic (As) wine is a traditional activity during the classic Chinese festival of Duanwu, colloquially known worldwide as the Dragon Boat Day. Arsenic wine is drunk on the morning of the fifth day of the fifth lunar calendar month to commemorate the death of Qu Yuan, a famed Chinese poet who drowned himself in protest of a corrupt government, and to protect against ill fortune. Although realgar minerals are characteristically composed of sparingly soluble tetra-arsenic tetra-sulfides (As₄S₄), purity does vary with up to 10% of As being present as non-sulfur bound species, such as arsenate (As^V) and arsenite (As^III). Despite, the renewed interest in As speciation and the bioaccessibility of the active As components in realgar based Chinese medicines, little is known about the safety surrounding the cultural practice of drinking As wine. In a series of experiments the speciation and solubility of As in a range of wines were investigated. Furthermore, a simulated gastrointestinal system was employed to predict the impact of digestive processes on As bioavailability. The predominant soluble As species found in all the wines were As^III and As^V. Based on typical As wine recipes employing 0.1 g realgar mL^− 1 wine, the concentration of dissolved As ranged from ca. 100 to 400 mg L^− 1 depending on the ethanol content of the preparation: with the As solubility found to be higher in wines with a lower proportion of ethanol. Based on a common 100 mL measure of wine with a concentration of 400 mg As L^− 1, the amount of soluble As would equate to around half of the acute minimal lethal dose for adults. This is likely an underestimate of the bioaccessible concentration, as a three-fold increase in bioaccessibility could be observed in the intestinal phase based on the results from the stimulated gastrointestinal system.     

合肥地区粘性土的自由膨胀率与液限的关系

文章从试验资料出发,对合肥地区粘性土的自由膨胀率与液限的相互关系进行统计分析,建立线性方程,根据方程由液限算出自由膨胀率,结合工程地质特征,可对粘性土的膨胀性进行判定。     

Assessment of the adhesion potential of kaolinite and montmorillonite using a pull-out test device

Bulletin of Engineering Geology and the Environment - The tendency of clay particles to stick other surfaces means it is adhesive and can cause clogging of tunnel boring machines. Clogging arising...     

Reactor design and kinetics study of 4,4'-dichlorobiphenyl photodecay in surfactant solution by using a photosensitizer and hydrogen source

The system design based on the photodegradation kinetics of 4,4'-dichlorobiphenyl (4,4'-DCB) in surfactant solution with the aid of solvents (acetone and/or squalane) has been studied. Organic solvents acetone and squalane were added as a photosensitizer and a hydrogen source, respectively, to achieve better photolysis performance. The quantum yield of 4,4'-DCB photodecay in Tween 80 micellar solution in the presence of added acetone was increased from 0.032 to 0.043 at its optimal condition. Acetone was shown to be an effective photosensitizer at low concentration, but an overdose would quench the reaction. Furthermore, the addition of squalane could further promote the photodechlorination of 4,4'-DCB in the Tween 80/acetone solutions for an additional 59% of rate improvement. However, an overdose of either solvent was found to cause UV light attenuation and to reduce the observed quantum yield. This effect has been justified and quantified in this study by a proposed light attenuation model, which has also been incorporated into the kinetic equation so that the resulted formula can be used to design the UV reactors for water and wastewater treatment works.     

A Comparison of a Statistical and Computational Fluid Dynamics Approach to Estimate Heat Release Rate in Road Tunnel Fires

Computational tools such as one-dimensional models or Computational Fluid Dynamics (CFD) have been used for the fire safety design of road tunnels. However, most of these analyses are performed using a specified fire source where the heat release rate (HRR) in the tunnel is fixed by the user and the influences of ventilation conditions and tunnel geometry are not considered. For a more realistic estimate, models need to incorporate these factors in their input. This paper discusses the use of a statistical approach previously developed by other researchers (Carvel and Beard, The handbook of tunnel fire safety. Thomas Telford Publishing, pp 184–197, 2005) and the use of a CFD approach to estimate the HRR in a road tunnel fire. As an application example, fire scenarios in which a light goods vehicle carrying wooden pallets are used to compare the estimation of the HRR using these two methods.     

产酸脱硫反应器中COD/SO42-比对硫酸盐去除率的影响研究

采用两相厌氧生物处理工艺的产酸相作为硫酸盐还原单元,以食用红糖为碳源,通过连续流实验,重点研究了产酸相中COD/SO42-值(C/S)对SO42-去除率的影响.在34±1 ℃、进水碱度(ALK)300～500mg/L、pH 6.0～6.2、氧化还原电位(ORP)-250～-350mV等条件下,当进水C/S＜2.0时,SO42-去除率小于81%;当进水C/S值为2.5～2.0时,SO42-去除率为90～81%;当进水C/S值为大于2.5时,SO42-去除率为90%以上.随着C/S值的降低,SO42-的去除效果会将有所降低.     

Risk Assessment for a Proposed Groundwater Abstraction Scheme in Strathmore, North-East Scotland: a Modelling Approach

The Lower Old Red Sandstones in northern Strathmore have favourable hydrogeological conditions for ground-water development. A scheme was proposed to abstract water in the north Esk catchment in order to augment water supplies to local villages, and a production borehole was drilled into the Edzell Sandstones to give a design yield of 2420 m³/d. However, this scheme has been abandoned because of concern that the abstraction would significantly reduce the flow in a nearby stream which is an important salmonid fishery.
This study demonstrates the potential value of using a stream-aquifer numerical model in an environmental risk assessment for the proposed scheme.     

A Global Model for Heat Release Rate Prediction of Cable Burning on Vertical Cable Tray in Different Fire Scenarios

Fire Technology - Cable fire risk analysis is important for fire protection design in  industrial as well as residential buildings. The vertical movement of the cable...     

Assessment of path choices on a country walk using a virtual environment

Virtual environments can provide landscape researchers new opportunities to explore aspects of landscape perception and response. A virtual environment requires a detailed 3D model of a place and the use of a high performance computer to allow people to explore it interactively. As with any new experimental tool, we should first establish the validity of the technique. This paper describes the process of model building for a section of the Dee valley in northeast Scotland, the development of software to support interactive exploration, and an experiment which was designed to answer some primary questions about validity and some secondary ones about local landscape preferences. The findings were encouraging for the further use of virtual environments and showed that people made choices in the virtual environment which fitted their stated preferences and were different from the choices other subjects made on the basis of still images.     

生命周期影响评价权重系数的确定方法探讨

随着生命周期评价应用的日益广泛，生命周期影响评价的完善也被提上日程。介绍了在影响评价中确定权重的三种方法，即专家法、层次分析法和线性回归方程法。为今后进行生命周期影响评价和研究提供了依据。     

Burning behavior of two adjacent pool fires behind a building in a cross-wind

With the global move towards performance based fire design, fire safety assessment in and around buildings becomes increasingly important. However, key knowledge gaps still exist concerning the behavior of fire swirling, which may be generated if one or more accidental fires are in the passage of the vortices behind an adjacent tall building. The present study is focused on the experimental investigations of the burning behavior of two pool fires behind 1/50 scaled tall buildings with heights varying from 0.565 to 1.165 m in a cross-wind. The objective is to gain insight of the effect of the distance between the two fires (D2), the distance between the fires and the building (D1), wind speed (V), and the height of the scaled building (H) on the burning behavior. Important conclusions have been drawn about the influence of D1 and D2 on the fuel mass loss rate, the influence of D1 on fire swirling, the influence of D2 on the possible merging of the two fires and the effect of wind speed on the mass loss rate. The results suggested the existence of a critical velocity for the cross-wind on the initiation of fire swirling and an approximate value was identified for the conditions in the tests. The investigations also covered the effect of height of the scaled building on the fuel mass loss rate and the occurrence of fire swirling. This relationship was found to be also dependent on the wind speed. Analysis of the results has led to some important recommendations to enhance the fire protection of tall buildings.     

Assessment of a camera pose algorithm using images of brick sewers

Further developments in an ongoing multi-disciplinary research programme concerning the automation of sewer surveys are reported. Previous papers have suggested a theoretical model for use in establishing a frame of reference for closed circuit television (CCTV) camera images of non-man-entry (NME) brick sewers, in order to enable quantitative observations to be automatically acquired employing computer vision techniques. Herein is discussed a simulation testing strategy designed to determine the model's predictive accuracy and thereby assess the corresponding assumptions made. Test results are presented which display robust model characteristics. Further developments are then considered in the context of in-service practice.     

Analysis and Modeling of Pedestrian Flow in a Confined Corridor Focusing on the Headway Distance and Velocity of Pedestrians

Fire Technology - In fire evacuation situations, at corridors, many evacuees are plagued by high density, low velocity, and long waiting time. Therefore, engineers have to consider the...     

Assessment of Tc-99 monitoring within the western Irish Sea using a numerical model

Water circulation patterns and associated material transport within a highly dynamic system such as the Irish Sea are complex phenomena. Although Tc-99 monitoring programme undertaken by the Radiological Protection Institute of Ireland provides a good insight to the material distribution on the east coast of Ireland, transport patterns within the Irish Sea have not been fully explored. In this study a validated transport model was used to hindcast transport of Tc-99 discharged from the Sellafield plant to determine extents of Tc-99 migration within the Irish Sea and reassess transit times to east coast of Ireland. Transit times are also estimated within a context of changes in meteorological conditions and fluctuations in discharges. Additionally, seasonal and inter-annual circulation patterns were examined.Relationships between discharge times and timing of far field concentrations are highly variable and are dependant on sea dynamics controlling the accumulation and removal of Tc-99 mass. Transport towards the Irish east coast, and consequently transit times, vary intra- and inter-annually, and depend on the prevailing hydrodynamic conditions resulting from meteorological conditions. The transit times from Sellafield to Balbriggan fall within the wide range of 30-240 days; with summer releases resulting in the shortest transit times. The model also indicated a strong relationship between summer concentration peaks on the east coast of Ireland and the strength of the Western Irish Gyre. Sudden increases of Tc-99 concentrations at Balbriggan coincide with peak of sea surface temperatures when the gyre is strongest and when advection is fastest.The adequacy of the current radionuclide monitoring programme within the western Irish Sea is evaluated, and recommendations are made for the development of a more optimised monitoring programme.