多孔陶瓷板红外线辐射器头部能量损失系数的确定

本文提出了多孔陶瓷板工外线辐射器部能量损失系数Ｋ１的计算方法。分析了多孔陶瓷板开孔率、燃气种类、板面温度、火孔热强度、燃烧器结构及燃气一空气混合物进入火道前预地Ｋ３的影响，并指出了由此产生的对引射及燃烧稳定性的影响。．     

金属网对陶瓷板燃气红外辐射器性能的影响

在多孔陶瓷权燃气红外辐射器热平衡理论分析的基础上,通过一系列对比实验,得到出外加金属网对多孔陶瓷板燃气红外辐射器燃烧完全度及辐射效率的影响的规律。     

燃气红外线燃烧技术的探讨

以金属纤维燃烧器及多孔陶瓷板燃烧器为例，阐述了气体表面燃烧技术的低污染排放性能及应用上的特点，并将这两种燃烧器与大气式燃烧器的性能进行了比较。     

多孔陶瓷板红外燃烧器头部能量损失系数计算

多孔陶瓷板红外燃烧器特有的头部结构使得针对大气式燃烧器头部能量损失系数K₁的计算方法不再适用。推导出适用于多孔陶瓷板红外燃烧器的K₁修正计算公式,建立单火孔完全预混燃烧模型,将利用Fluent软件数值模拟得到的火孔内预混气体的沿程温度分布函数与K₁修正计算公式结合,经迭代计算得到K₁计算值,与实测数据对比,验证了该方法的可靠性。模拟分析了K₁受燃烧器热负荷、陶瓷板热导率和孔隙率的影响,结果显示：随着燃烧器热负荷增加,火孔内预混气体的沿程温度和K₁计算值均呈下降趋势,且热负荷越小,下降幅度越明显。K₁计算值受陶瓷板热导率影响不大,仅随热导率增加呈现小幅上升趋势。陶瓷板孔隙率越大,K₁计算值越大;火孔内预混气体沿程温度在靠近入口的区段随着孔隙率增大而下降,在靠近出口的区段随着孔隙率增大而升高。     

多孔陶瓷板红外线燃烧器的着火过程

研究了X型多孔陶瓷板燃气红外线燃烧器的着火过程及其与一般着火过程的区别。     

多孔金属板与多孔陶瓷板在燃气灶具中的性能对比

本文对新型粉末冶金多孔金属板和已广泛商用的多孔陶瓷板在家用燃气灶具中的应用性能进行了实验对比研究,验证了多孔金属介质在燃气灶具中应用的可行性,揭示了两种多孔介质板面在点火后与熄火后的温度变化情况。同时,使用Fluent进行数值模拟,探讨了介质的不同导热系数对燃烧性能的影响。为多孔介质红外辐射燃烧器板面材料的选择和优化提供了参考依据。     

复合层多孔陶瓷板燃气辐射器的研究

复合层多孔陶瓷板燃气辐射器的研究徐吉浣，施惠邦，徐振平，徐基璇（同济大学，上海２０００９２）１概述燃气红外加热技术在工业和民用燃烧设备上得到了广泛的应用。实践证明它比传统的对流加热具有投资省、启动快、效率高、污染少等优点。经过特殊设计的红外辐射器还能...     

陶瓷板红外线燃气灶节能效果的分析

分析了陶瓷板红外线燃气灶热效率比大气式燃气灶高的原因：具有陶瓷板辐射体，辐射效率高；燃气燃烧需要的过剩空气系数小，致使理论燃烧温度高，增强了换热，减少了排烟损失；锅支架高度小，有利于增加换热量和减小向周围的辐射散热损失。     

泡沫陶瓷外墙外保温系统应用技术

介绍了泡沫陶瓷板的生产工艺过程、性能特点及其外墙外保温系统组成材料的技术要求,重点叙述了泡沫陶瓷板外墙外保温系统的应用技术要点,认为泡沫陶瓷板的热工性能和燃烧性能突出,可以满足各类建筑的多种部位和各种工程做法的要求,合理选用后,综合社会经济效益明显。     

陶瓷质红外线辐射器的研究

煤气加热式红外线辐射器是利用低压煤气,如发生炉煤气、焦馏煤气、水煤气、天然煤气或其他可燃性气体,如甲烷、乙炔、丙丁烷等作燃料与一次空气混合在多孔陶瓷板表面成无焰燃烧。当板灼热后辐射出大量的红外线热能。这种辐射器不需要二次空气,燃烧较为完全,而且设备简单,操作方便,热效率高,成本低,是一种既经济又实用的热辐射源。煤气红外线辐射器的红外线波长为2.0～3.0微米左右。红外线能穿过周围介质而透入物质内部并转换为热能,可大大地加速物体热加工的过程。红外线辐射器的应用范围很广,可     

红外燃烧器火孔沿程阻力系数的分析

对红外燃烧器头部能量损失系数计算中的炎孔沿程阻力损失提出了修正，提出火孔内的温度分布对流动造成的影响。用已燃段内的加权平均温度（着火温度、最高温度、火孔出口温度）来代替火孔出口湿度进行近似计算。对于人工煤气，在燃烧器设计时应通过实验确定火孔内温度分布的曲线后计算阻力系数。     

长廊型高层建筑火灾烟气控制模式的效果比较

为研究走廊中常见烟气控制模式的效果,采用数值模拟与全尺寸长廊实验相结合的方法,对采用挡烟垂壁、机械排烟和空气幕等多种组合的防排烟模式的防排烟效果进行分析.比较各种模式下烟气的温度分布、质量分数分布以及烟气沉降时间,设计5种排烟模式.结果表明:防烟空气幕效果明显.采用前室部分加压并在前室门口设置防烟空气幕,同时开启两个排烟口的排烟模式具有最佳的烟气控制效果,其排烟效率达到74.52%.     

How groundwater seepage and transport modelling software can be useful for studying gaseous transport in an unsaturated soil

The aim of this paper is to show how standard hydrogeologic software, usually used to model contaminant transport in groundwater under unsaturated conditions, can also be used to model gas transport in unsaturated porous media. Physical processes involved in the interaction between the atmosphere and the unsaturated soils are considered: transport by diffusion through the air and the groundwater, exchange between the liquid and gas phases and consumption. These physical processes are incorporated into the governing equations of a groundwater numerical code; by considering air, contained in the unsaturated soil, as water in the seepage numerical model, the air effectively becomes fluid within the numerical code. Then, the investigated gas is defined as the contaminant in the transport model, which is transported by -the air for the modeller-, and -water for the numerical code-. The over-riding assumption is that the air profiles and, therefore, water profiles of volume contents remain constant. The approach is illustrated using two examples, which consider the transport of oxygen. The first deals with oxygen distribution through a laboratory-cell diffusion containing reactive mining tailings. The second deals with the oxygen fluxes through the vadose zone, between the atmosphere and an unconfined aquifer's water table. Both examples consider different cases of oxygen consumption.     

钢筋混凝土框架结构底部相邻两柱失效的抗连续倒塌性能研究

为研究钢筋混凝土结构在角柱和相邻边柱同时失效情况下的抗连续倒塌性能,采用12点等效均布荷载加载系统,对移除角柱和相邻边柱后的钢筋混凝土梁-板-柱子结构进行PUSHDOWN加载,并对钢筋混凝土子结构的破坏模式、承载能力、变形能力、钢筋局部应变、支座水平位移及边梁扭转变形进行分析。试验结果表明：角柱和相邻边柱同时失效的钢筋混凝土梁-板-柱子结构反应与悬挑板相近,梁与板无法形成有效的压拱机制、悬链线机制或薄膜机制来抵抗连续倒塌的发生。采用有限元软件DIANA建模对试验结果进行了数值模拟分析,证明了数值模型的合理性。采用塑性铰线法对试验屈服荷载和第一极限荷载进行分析,理论分析结果表明,与试验结果相比,塑性铰线法的分析结果偏于保守。     

软土工程中的非线性流变分析

根据岩土材料的室内蠕变试验结果，提出了一种理论模型和用于数值分析的计算公式，并对上海地铁一深基坑开挖工程进行有限元分析。计算结果与现场实测资料相当吻合     

Kriging Numerical Models for Geotechnical Reliability Analysis

When the performance function is an implicit numerical model, geotechnical reliability analysis can be challenging due to the coupling between the deterministic numerical evaluation and reliability analysis. Previously, the kriging method was used in geotechnical engineering for modeling the spatial variability of soil properties. In this paper, we illustrate a first-order reliability analysis method based on a kriging approximation of the deterministic numerical model. The key idea in this method is to first calibrate a kriging model to approximate the deterministic numerical model, and then to evaluate the failure probability based on the kriging model. As any stand-alone software for deterministic geotechnical numerical analysis can be potentially used to generate samples for calibrating a kriging model, it can then be ultimately used for a reliability analysis. As such, this method provides a practical way for practitioners to perform reliability analysis based on existing deterministic geotechnical software. The effectiveness of the suggested method is illustrated through a pile foundation example, a shallow foundation example, and a slope example in which the performance functions do not have explicit forms. The kriging method is used here as a tool for interpolating and approximating deterministic numerical models. The present paper does not address any type of spatial variation of soil properties.     

Reducing deformation effect of tunnel with Non-Deformable Support System by Jointed Rock Mass Model

Numerical modeling has been used widely in mining and construction industries in recent years. The most important issue in engineering projects designed with numerical modeling is accurate modeling of rock mass behavior. If the rock mass behavior is modeled accurately, fewer problems will be faced during field application of projects. Selection of the true material model is a very important issue in numerical modeling for the tunnel projects. Non-Deformable Support System (NDSS), which will be mentioned in the scope of this research, does not mean that it does not permit any deformation or is a very stiff system. NDSS is a support system that does not permit deformations exceeding specified deformation amounts which are calculated with determination of the accurate rock mass behavior by the true material model and it must be evaluated with support system and excavation advance specifically. The origin of the paper is that numerical modeling provides more comfortable results in tunneling in case one can determine rock mass deformation and failure behavior appropriately. In (NDSS), however, support system element can only be determined by proper numerical modeling analysis. Moreover, deformation values determined by NDSS analysis are accepted as limit values. Therefore, applied support system should be within deformation tolerance limits determined by NDSS analysis. Briefly, this paper is related to NDSS that should be determined by numerical modeling analysis.In this research, in regard to the excessive deformations in T-35 tunnel which is one of the 33 tunnels of Ankara–Istanbul High-Speed Railway Project, results of the in situ measurements in the tunnel excavated with the new developed NDSS and results of the numerical model made with Jointed Rock Mass Model have been compared. It is determined that the results of the numerical modeling and the in situ measurements are very consistent with each other.     

Factors contributing to change in the European port system

Before 1989, West European ports were vying with one another to be in a competitive position in preparation for the cessation in 1993 of internal customs barriers within the European Common Market. The sudden opening up of Eastern Europe in 1989 gave an additional dimension to the competition, and the expected opening of the English Channel tunnel in 1993 will augment the challenge. As if these changes were not enough, European ports had to respond to a host of other trends and conditions. The stakes are high: experts have predicted that in the end, there will be only one central hub port, or at best three or four, and that other ports will have to serve as feeder or specialized ports.     

Study of ground vibrations induced by railway traffic in a 3D FEM model formulated in the time domain: experimental validation

In this paper, a three-dimensional numerical model is applied for studying railway vibrations. The numerical model is based on finite element method formulated in the time domain with an implicit scheme of integration. In the first part of the paper the numerical approach is briefly described. An uncoupled scheme is applied: (i) firstly the train loads are calculated taking into account dynamic excitation with a 2D vehicle-track model; (ii) the computed loads on each sleeper are introduced into a 3D numerical model, developed in the commercial code Plaxis, which is used to simulate the wave propagation in the ground. In the second part of the paper a real case study, located in Portugal, is presented, being used for the experimental validation of the proposed model. The numerical results of ground vibrations show an acceptable agreement with real measurements. Therefore, the proposed approach can be used as a reliable prediction tool based on PLAXIS software, which allows simulating railway vibrations in some specific cases such as soft soils, inhomogeneous geometries in the longitudinal direction of the track and transition zones.