物质热稳定性评估方法研究

文章分析了与物质热稳定性有关的特性参数，比较了评估物质热危险性的常用试验方法，以加速量热仪为例研究了绝热量热测试方法在评估物质热稳定性方面的应用。     

木材热重试验及动力学分析

选取文物建筑中 4 种常见的木材为研究对象,对其在 5 K/min 的升温速率下进行热重实验。将木材的热解过程分为 4 个阶段,木材热失重主要在第二和第三阶段进行。对不同温度阶段下的热解过程进行分析,并建立了木材热解的动力学方程,求出热解动力学参数。木材热稳定性从高到低依次为：杉木热稳定性最好,楠木次之,白松和红松稳定性相当。     

典型火灾可燃物生物质热失重特性比较研究

对十种生物质的热解行为进行了热重分析(TG)和差分热重分析(DTG)试验研究。深入研究了气氛、样品种类、含水率对生物质热失重曲线特征的影响，建立了“分阶段一级反应动力学模型”，计算了生物质不同气氛下的动力学参数。     

过硫酸铵的热不稳定性分析

选取常见的过氧化物过硫酸铵为代表，模拟影响其热不稳定性的不利条件，运用热分析实验技术，分析过硫酸铵分解反应机理，计算动力学参数和热不稳定性参数，分析过氧化物的热不稳定性与过氧化物火灾之间的关系，建立热解模型，找出造成自燃着火的条件和规律，确定其安全与危险之间的临界条件。     

木材的燃烧性能研究--锥形量热计法

采用锥形量热计(Cone Calorimeter)对多种木材在阻燃处理前后的燃烧性能进行测试，并分析木材在阻燃处理前后燃烧性能的变化规律。试验表明，经阻燃处理的材料其热释放速率显著降低，推迟了燃烧波峰出现的时间，因而可以安全应用于建筑室内。而普通的木材由于热释放速率大而具有很大的火灾危险性。研究还发现普通木材燃烧都会形成两个波峰。锥形量热计能精确测量材料的热释放速率、烟密度等数值，对于研究材料的燃烧性能和正确使用具有重大的现实意义。     

低辐射强度下古建筑木构件材料的燃烧特性

为研究古建筑木构件材料在火灾下的燃烧特性,使用锥型量热仪对古木材试样的点燃时间、临界辐射强度、热释放速率、燃烧气体中CO2体积分数等燃烧特性进行试验研究。试验发现3种不同厚度试样的临界辐射强度分别为8.81,9.40,10.55 kW/m2。试样厚度增加会使古木材点燃时间延长,临界辐射强度增大,材料的热释放速率所形成的双峰值曲线的峰值降低。燃烧气体中CO2体积分数曲线与热释放速率所绘制出的曲线的形态一致,同一厚度的试样在不同辐射强度下其燃烧特性呈现出显著区别。与新木材相关燃烧特性参数对比,劣化后的古木材临界热辐射强度降低、点燃时间减小,5 min内平均热释放速率较高。研究表明,古建筑木构件材料燃烧特性有显著变化,可为古建筑火灾研究提供参考。     

某体育场馆地源热泵系统应用与节能分析

地源热泵系统是一种依赖地源的高效供能技术，因此做好地源参数的评估研究至关重要。采用岩土热响应试验的方法对地质条件、岩土热物性、换热孔的换热能力等参数进行了分析，为地源热泵系统实施的可行性论证、设计和施工提供依据。     

控制参数对色温引发的热感觉及热舒适实验结果的影响

由触觉引起的热感觉和热舒适已经有相当系统和完善的研究,然而在由光环境引起的热感觉和热舒适的研究中却存在着诸多矛盾.矛盾主要集中在色温对热感觉及热舒适的影响程度上.当比较20世纪90年代以前的论文结论和20世纪90年代以后的论文结论时,这种矛盾尤为明显.致力于找到这种矛盾的诱因,并为此类研究推荐了合适的实验控制参数组合.通过分析生理学和心理学的研究结论,总结出光环境通过两种不同途径对体温调节、热感觉、热舒适的影响和基于各个途径的限制条件.总结此类研究中应该着重控制的实验参数.通过对此类研究的实验方法的分析,得到此类论文产生矛盾的根本原因,并由此给出可以产生可信研究结论的实验控制参数组合.     

不同行为方式下人体热感觉与室内环境之关系

对影响人体热舒适度的室内物理参数及瞬态热的影响关系进行了详细分析，并对不同行为方式下人体主观因素进行了阐述，指出设计人员在设计时应考虑诸多因素，不同的行为方式采取不同的设计，以使人体达到热平衡的理想状态。     

基于城市形态参数的沈阳地表热环境评估方法及规划响应

掌握城市空间形态特征对热环境的影响机理是提升城市气候适应性的关键,构建科学的热环境效应预测模型是改善城市气候环境的有效途径。以沈阳市为研究对象,建立表征空间容量和形态特征的参数集,通过与地表温度的相关性分析识别了关键参数,采用主成分分析法构建了面向城市规划的热环境指数评估模型。研究结果表明：在不同的形态参数中,分别以叶面积指数、建筑容积率、天空开阔度与城市热环境的相关显著性更高,由热环境指数评估模型形成的沈阳市热环境空间分布图,较好地反映了研究区热环境效应分布现状。由此划分了沈阳市热环境空间单元,根据模型的参数构成及空间单元分布的情况,有针对性地提出了城市尺度的热环境格局优化和场地尺度的形态量化导控策略,为改善城市热环境效应提供了可操作性强的规划指标。     

Validation of data analysis routines for a thermal probe apparatus using numerical data sets

Most thermal properties of construction materials used in the analysis of building performance have been measured under laboratory conditions, using a guarded hot box or hot plate apparatus. As a consequence, these properties seldom reflect the impact of actual conditions (especially moisture content) on the values of thermal conductivity and diffusivity. Hence there is a need to develop techniques that take into account local conditions, and measure building material properties in situ. One option available is the use of a thermal probe. The thermal probe technique is based on creating a line source in a material sample and measuring the temperature rise in the sample in reaction to heat being applied. Obviously the data analysis routines used to calculate thermal conductivity and diffusivity based on the temperature rise observed are crucial to the success of the technique. This work has used transient thermal simulation of a model representing a line source in an infinite material sample to generate a set of numerical data sets to validate analysis routines in conjunction with an experimental thermal probe apparatus. Findings show that by careful application of these routines, a close agreement with simulation input values can be achieved, with errors of less than one percent. This validates the analysis routines and provides a deeper appreciation of the theoretical behaviour of a thermal probe.     

Probabilistic modeling of graded timber material properties

The probabilistic modeling of timber material characteristics is considered with special emphasis to the modeling of the effect of different quality control and selection procedures used as means for quality grading in the production line. It is shown how statistical models may be established on the basis of the same type of information which is normally collected as a part of the quality control procedures and furthermore, how the efficiency of different control procedures may be quantified and compared. The tail behavior of the probability distributions of timber material characteristics plays an important role in the overall probabilistic modeling. Therefore a scheme for estimating the parameters of probability distribution parameters focusing on the tail behavior has been established using a censored Maximum Likelihood estimation technique. The proposed probabilistic models have been formulated such that they may readily be applied in structural reliability analysis and their format appears to be appropriate for codification purposes of quality control and selection for grading procedures.     

不同温度下砂岩三点弯曲破坏的特征参量研究

 基于三点弯曲试验研究不同温度影响后平顶山砂岩的特征参量,重点探讨热处理后砂岩破坏的弹性模量、损伤参量及延性比的变化。提出一种新的分析岩石材料性能的参数,即数值弹性模量,这大大方便通过试验方法来获取弹性模量。基于不同温度下弹性模量的变化及Lemaitre损伤理论,定义热损伤,并发现分段的四次多项式能较好拟合岩石等脆性材料热损伤与温度的关系,并由此把热损伤分为4个阶段,即不稳定热损伤阶段、初始热损伤阶段、稳定热损伤阶段和快速热损伤阶段。最后,借用混凝土结构工程的概念,采用延性比来判别热处理后砂岩的脆–延转变特性,该值大于2时砂岩开始具有延性性质。     

Thermal dynamic transfer properties of the opaque envelope: Analytical and numerical tools for the assessment of the response to summer outdoor conditions

The reliable estimation of buildings energy needs for cooling is a crucial issue in the implementation of the EPB Directive 2010/31/EU (formerly 2002/91/EC), especially in central and southern Europe climates. On this purpose one of the main topics is to predict the behavior of the opaque envelope subjected to variable boundary conditions. The EN ISO 13786:2007 technical standard assumes sinusoidal boundary conditions and introduces dynamic thermal characteristics.The aim of this paper is to assess the deviation arising by the use of different approaches for the calculation of the dynamic thermal characteristics of an opaque envelope element under periodic non sinusoidal boundary conditions. The EN ISO 13786 procedure has been firstly applied by decomposing the external forcing temperature by means of the Fast Fourier Transform (FFT) analysis. A comparison with different approaches, such as Finite Difference Methods (FDM) and Transfer Function Methods (TFM), has been carried out.The predictions of the EN ISO 13786 with a sinusoidal forcing temperature (i.e., standard approach) have also been assessed, comparing the results to the ones obtained through the FFT analysis. Furthermore, corrections to the periodic thermal transmittance and to the time shift have been proposed, in order to improve the explicative worth of those parameters.     

圆形钢管混凝土柱中钢-混凝土界面接触热阻的理论分析

目前现有不多的计算受火条件下钢-混凝土组合结构温度场方法中,一个主要的不足是忽略了钢与混凝土界面处接触热阻的影响,这将对钢-混凝土组合结构温度场的精确分析、高温下结构(构件)的力学性能以及结构(构件)耐火极限的精确分析产生一定程度的影响。采用综合考虑钢材和混凝土热物理参数的方法进行分析推导,通过求解热传导方程导出了圆形钢管混凝土柱中钢管内壁与核心混凝土间接触热阻的数学表达式。研究为进一步精确分析高温下钢管混凝土柱的力学性能及耐火极限提供了一种新的方法。     

Using artificial neural networks for calculation of temperatures in timber under fire loading

Artificial neural networks have been used in recent years as a tool to model properties and behavior of materials in many areas of civil engineering applications. Because of their ability to learn and adapt they can be used to find complex relations between different properties. In the present paper artificial neural networks are used for predicting the temperatures in timber under fire loading. The artificial neural network model has been trained and tested using available numerical results obtained using design methods of Eurocode 5 for the calculation of temperatures in timber under fire loading. A multilayer feed forward network has been used with input data arranged in a format of three input parameters that cover the density of timber, the time of fire exposure and the distance from exposed side and the output parameter being the temperature in timber. The training and testing results in the neural network model have shown that neural networks can accurately calculate the temperature in timber members subjected to fire.     

Adaptive thermal comfort in primary school classrooms: Creating and validating PMV-based comfort charts

In this research the thermal comfort and thermal comfort parameters for children in primary school classrooms has been investigated. Actual thermal sensation and clothing insulation of children (age 9–11) in non-air-conditioned classrooms in three different schools in the Netherlands have been obtained. Results are available for a total of 24 days, covering winter, spring and summer conditions (year 2010). Questionnaires have been applied to obtain the actual thermal sensation and clothing insulation in the morning and afternoon of regular school days. In this period physical parameters (temperature, relative humidity, etc.) were recorded as well in order to derive the PMV.     

A New Fire Resistant Light Mineral Wool

A comprehensive research project on the fire performance of a new light mineral wool has been carried out at ETH Zurich in collaboration with the Swiss Federal Laboratories for Materials Science and Technology (EMPA). A large number of small-scale fire tests permitted the analysis of different parameters on the fire performance of the new mineral wool. The results of the fire tests allowed the verification and calibration of thermal properties used for thermal finite element (FE) analysis. Based on an extensive FE parametric study, the coefficients for the new mineral wool to be used in the design model for the verification of the separating function of light timber frame wall and floor assemblies were calculated. The paper first describes the main results of the experimental and numerical analyses. Then, the calculation of the coefficients for the new mineral wool to be used in the design model are presented.     

Model for predicting the axial strength of joints made with glued-in rods in sawn timber

Joints made with glued-in rods in sawn timber have been used for over 40 years in timber engineering, both for joint design in new constructions as well as in the repair of wood elements damaged by humidity or xylophage attack. One of the problems limiting the use of these types of joints is the absence of legislation regulating their sizing and design. Although EuroCode has given some proposals for estimating the load capacity of these joints, in practice, destructive testing must be performed for each specific case. Recent studies have offered design criteria and sizing restrictions, in most cases, for elements of glued laminated timber. Our research group has been studying the behavior of these joints in sawn timber for several years. The objective of this research is to determine the influence that different joint materials and geometric parameters have on their axial strength. A broad experimental study was performed on joints made with threaded steel rods glued with different types of adhesives and in different hardwood species. Over 400 specimens were tested with different geometric configurations, varying anchorage length, rod diameter and adhesive thickness. This paper presents a summary of the results obtained in the experimental analysis and proposes a model for predicting joint strength in sawn timber. Similarly, a comparative study of our design proposal is presented with the most recent equations for glued laminated timber connections.     

锂离子动力电池用气凝胶隔热材料研究进展

近年来,新能源汽车行业发展迅猛。锂离子电池因其能量密度大、循环寿命长等优势成为应用最广泛的动力电池,但其在极端条件下存在热失控安全问题。气凝胶作为一种新型纳米多孔隔热材料,复合材料耐温可达1000℃以上,其凭借优异的隔热性能及轻质、防火、环保等特性,被逐渐应用于新能源汽车电池电芯隔热防火。本文介绍了锂离子电池热失控现象及热防护措施,常用的气凝胶隔热材料及其应用于锂电池中的性能优势,并与传统动力电池隔热材料进行对比,最后对其应用前景进行展望。