预应力预制叠合楼板耐火性能参数分析

在合理选择混凝土和预应力筋材料的热工参数、高温力学参数的基础上,采用有限元分析软件ABAQUS建立底面受火的预应力预制叠合楼板的高温热力学模型,计算结果得到已有试验结果的验证。对影响预应力预制叠合楼板高温力学性能的各参数进行有限元分析,结果表明:荷载水平和耐火保护层厚度对叠合楼板耐火性能的影响显著,混凝土强度、预应力筋截面配筋率等参数对叠合楼板的耐火性能影响较小,可以忽略不计;耐火保护层厚度一定时,叠合楼板的耐火极限随荷载水平的提高而降低;荷载水平一定时,叠合楼板的耐火极限随耐火保护层厚度的增加呈非线性提高。在ISO-834标准火灾作用下,叠合楼板跨中挠度变化率速率大于L2/(9000d)可作为其达到耐火极限的判别标准。选取荷载水平、混凝土保护层厚度两个重要影响参数进行分析,提出了叠合楼板的耐火极限取值建议,为预应力预制叠合楼板的抗火设计提供技术参考。     

旋转火焰动力学特性的研究

在森林火灾中，出现旋转火焰的可能性很大。在大气环境中，由于局部温度的不均匀，从而导致气体的密度不均匀，这种气体密度的不均匀分布必然会在火焰内部和其周围环境之间产生一个压力差，引起气体的流动，同时由于火焰内部的斜压性，在受到地球Coriolis力的影响时，使火焰产生旋转，形成旋转火焰；同时，Coriolis力也会影响到旋转火焰的方向性。     

Quantification of inherent safety aspects of the Dow indices

The Dow fire and explosion index (F&EI) and chemical exposure index (CEI) have been successfully implemented in a Visual Basic environment as a tool for the inherent safety assessment of chemical processes. Subprograms were developed to quantify the inherent safety aspects of the Dow indices. These aspects are presented graphically with the indices on the vertical axis and an inherent safety indicator on the horizontal axis. Dow indices of the MIC storage unit involved in the Bhopal disaster were evaluated to quantify the effects of process temperature, pressure and inventory of hazardous materials on the index values.

As operating pressure was reduced, the F&EI decreased in accordance with the principles of inherent safety. The change in F&EI due to reduction of inventory was more significant than that resulting from pressure reduction. The results show that the F&EI change, given the same range of the independent variables (quantity of hazardous materials, operating temperature and pressure), is larger when a unit in the process area is evaluated compared to a unit in a storage area (tank farm). Reduction of the inventory of hazardous materials had no direct effect on the CEI for vapor releases, whereas the size of the hole diameter impacted the CEI to a great extent. However, there is a significant change in the CEI as the inventory of materials decreases for liquid releases involving temperatures above their flash and boiling points. Pressure reduction decreases the CEI, whereas temperature reduction leads to an increase in the CEI when these parameters are treated independently.     

中国舰船消防现状及发展趋势

本文从体制、装备、消防教育等方面简略介绍了中国舰船消防体系，对目前舰船火灾及消防形势进行了分析，提出了舰船消防面临的任务和主要课题，并对中国舰船火灾及其防治前景进行了探讨．     

Function of Basic Fire Research

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Unignited High-Pressure Methane Jet Impinging a Pipe Rack: Practical Tools for Risk Assessment

Although the diffusion of its storage and transport under liquefied conditions, nowadays it is common to have methane in gaseous form in several industrial applications. This leads to safety implications to be considered: hazards are linked to both the high-pressure at which the gas is kept and to its flammability. Scenarios where flammable jets impact an obstacle are of paramount importance because of their possible occurrence. Following a numerical approach, literature shows up that their assessment can be reliably performed by means of only Computational Fluid Dynamics tools. However, despite the improvements of computing power, Computational Fluid Dynamics costs still limit its use in daily risk analysts’ activities. Therefore, considering an accidental jet-obstacle scenario of industrial interest, the present work investigates how a pipe rack can influence the development of a high-pressure methane jet. Based on a Computational Fluid Dynamics analysis, main achievements of this work are a simple criterion able to identify the situations where the pipe rack does not influence the high-pressure methane jet behavior, therefore allowing to identify the scenarios where simpler models can be used (i.e., analytical correlations known for the free jet situation), and, if present, a simple analytical relationship that roughly predicts the influence of the pipe rack without the need of performing complex Computational Fluid Dynamics simulations.     

石油化工企业火气系统安全性评估方法

火气系统属于减缓层内的安全仪表系统,在减轻事故后果方面起到非常重要的作用。针对传统火气系统只满足功能需求设计的不足,提出与风险分析相结合的火气系统设计新理念,以具体案例分析场景危险性,通过覆盖率、可用性、有效性等参数,定量场景的潜在生命损失,以风险降低为目的,量化计算事故后果和频率,评估火气系统的有效性。     

Development of a framework for fire risk assessment using remote sensing and geographic information system technologies

Forest fires play a critical role in landscape transformation, vegetation succession, soil degradation and air quality. Improvements in fire risk estimation are vital to reduce the negative impacts of fire, either by lessen burn severity or intensity through fuel management, or by aiding the natural vegetation recovery using post-fire treatments. This paper presents the methods to generate the input variables and the risk integration developed within the Firemap project (funded under the Spanish Ministry of Science and Technology) to map wildland fire risk for several regions of Spain. After defining the conceptual scheme for fire risk assessment, the paper describes the methods used to generate the risk parameters, and presents proposals for their integration into synthetic risk indices. The generation of the input variables was based on an extensive use of geographic information system and remote sensing technologies, since the project was intended to provide a spatial and temporal assessment of risk conditions. All variables were mapped at 1 km² spatial resolution, and were integrated into a web-mapping service system. This service was active in the summer of 2007 for semi-operational testing of end-users. The paper also presents the first validation results of the danger index, by comparing temporal trends of different danger components and fire occurrence in the different study regions.     

A Hierarchical Bayesian model of wildfire in a Mediterranean biodiversity hotspot: Implications of weather variability and global circulation

In this study we combined an extensive database of observed wildfires with high-resolution meteorological data to build a novel spatially and temporally varying survival model to analyze fire regimes in the Mediterranean ecosystem in the Cape Floristic Region (CFR) of South Africa during the period 1980-2000. The model revealed an important influence of seasonally anomalous weather on fire probability, with increased probability of fire in seasons that are warmer and drier than average. In addition to these local-scale influences, the Antarctic Ocean Oscillation (AAO) was identified as an important large-scale influence or teleconnection to global circulation patterns. Fire probability increased in seasons during positive AAO phases, when the subtropical jet moves northward and low level moisture transport decreases. These results confirm that fire occurrence in the CFR is strongly affected by climatic variability at both local and global scales, and thus likely to respond sensitively to future climate change. Comparison of the modelled fire probability between two periods (1951-1975 and 1976-2000) revealed a 4-year decrease in an average fire return time. If, as currently forecasted, climate change in the region continues to produce higher temperatures, more frequent heat waves, and/or lower rainfall, our model thus indicates that fire frequency is likely to increase substantially. The regional implications of shorter fire return times include shifting community structure and composition, favoring species that tolerate more frequent fires.     

A model for wildfire prevention planning in game resources

The high incidence of hunting activity and forest fires in different ecosystems (particularly in Mediterranean ecosystems) requires a model, which allows for the comprehensive management of hunting resources and estimating the potential damage caused by this type of disturbance. This paper proposes a model for evaluating the socio-economic effects of forest fires on hunting. Its cornerstone lies in evaluating hunting resource availability for each ecosystem within its territorial mosaic. Each game management unit (GMU) is identified by vegetation structure and habitat type. It presents a novel approach in which the economic value of each game management unit is linked to potential forest fire damages. The effect a forest fire has on an entire ecosystem depends on the intensity of its flames. A sample study was undertaken in the province of Huelva in Andalusia (southern Spain). The socio-economic hunting vulnerability of the province of Huelva was 45,188,000€. The results obtained confirmed the need for an economic appraisal of non-forest products in the forest and other woodland areas. Geographic Information System increases the flexibility and simplicity of our methodology which permits immediate extrapolation to other agroforestry territories.