外飘窗顶板结露现象浅析

本文分析了住宅外飘窗结露现象产生的原理和原因,并对顶板结露的治理和预防住宅外飘窗结露现象进行了初步探讨。     

建筑围护结构内结露现象分析与预防

本文通过分析建筑围护结构内结露现象的原因,阐述结露现象的预防重点,并探讨防止结露问题的途径。     

上海地区房屋墙面结露的调查分析

房屋墙体结露现象一般多见于北方采暖地区,而上海地区位于夏热冬冷地区,墙体结露现象并不常见。然而近期许多新建住宅项目,在投入使用后不久也出现了房屋墙体结露现象,大部分出现了墙面发霉等严重影响使用功能的问题。通过近年来碰到的一些工程案例,对上海地区房屋墙面结露的特征进行了描述,对产生的原因进行了分析,对处理方法进行了探讨。     

辐射空调末端防结露控制方案比较

辐射空调制冷在高湿高热的场所出现辐射末端结露的现象,成为该技术发展的最大障碍。因此,如何更好地解决该系统出现的辐射末端结露问题需得到足够的重视。论文介绍了结露的原因和危害,分析了防结露的原理,并着重对几种末端防结露控制方法进行比较,得出了更合理的末端防结露方案。     

卷烟工业厂房屋面防结露技术研究与应用

针对建筑物室内结露,严重影响其使用功能这一现象,对拟应用硬质玻璃棉板柔性屋面系统防结露技术进行了研究,通过分析计算结露温度和最小热阻值以及保温层厚度,使其达到了防止屋面结露的目的。     

利用组合通风改善沿海地区地下车库结露状况

针对南方沿海地区梅雨期地下建筑表面结露现象,通过用CFD对某非保温地下车库结露问题研究发现,利用诱导通风、空气幕、低温空气幕和强力风机的策略组合方法可以消除恶化的结露现象。     

大型冷库防结露工艺探讨

基于一个综合类大型冷库建设与运维阶段的实践，分析了冷库结露现象产生的原因。结合多个类似冷库的经验教训，使用聚氨酯、氰凝、PIR库板等材料解决了冷库闷顶和防火卷帘门结露的问题。以上2种防结露措施有效减少了结露现象的产生，从而显著降低冷库后期运维的成本，同时提高了冷库使用的安全性。     

贵州某卷烟生产厂房结露问题分析

卷烟厂联合工房结露问题是烟草行业技术改造问题中的一个难点,各个卷烟生产企业联合工房均存在不同程度的结露现象。针对这种情况,笔者详细考察了多个卷烟厂,分析查找了其结露现象产生的根源,并提出了合理的建议和解决办法,以期对同类卷烟厂技术改造能提供一些新的思路。     

寒冷地区通信机房内部结露可能性分析

笔者曾经对寒冷地区的通信机房提出过一系列节能措施，但未得到较好的推广。问题的关键在于．有关管理部门对采取笔者所提出的节能措施后，机房在冬季是否会产生结露现象存在疑虑。本文通过对建筑结露条件和机房内部气候条件进行分析，找出通信机房不可能结露的确凿依据，在理论上证实了通信机房内部不存在结露的可能性．并对短时间内的轻微结露现象提出了简捷有效的防治措施。     

建筑冷凝结露分析

本文通过对建筑中所产生的结露现象和原因进行分析和论述,讨论了防止结露的对策,并分析了产生冷凝结露的原理。并以具体的实例通过热工计算,指出墙体表面产生结露的条件,以及如何通过墙体保温的处理、技术改造来达到墙体不致产生结露,使室内人员生活在一个热舒适的建筑环境内。     

Analysis of geosynthetic tubes filled with several liquids with different densities

A two dimensional model of a geosynthetic tube sitting on a rigid horizontal foundation and filled with several separated liquids with different densities is proposed. The material from which the tube is made is a special synthetic fabric which is inextensible, perfectly flexible, and leakproof. Such a model is useful for modeling a consolidations process in the tube filled with a slurry. The equilibrium equations of the model are formulated. Unknown values like the pressure on the top and bottom of the tube, the tension in the geosynthetic fabric, the length of the contact zone between the tube and the rigid foundation are searched with respect to the given perimeter, the volumes and densities of liquids. Such a problem is solved by the Newton’s method. The initial approximation is obtained by solving a simplified problem with one liquid with the average density. The problem is implemented in a MATLAB code for geosynthetic tubes filled with two, three, and four liquids with different densities. The tubes filled with two different liquids are studied in more detail. The graphs of the relations are compared with the graphs for the tube filled with the single liquid whose density is the average of the densities of the liquids. The comparison enables to discuss the influence of the consolidation process on the height, the contact zone, the pressures and the tension of the tube. The results of the proposed model for a tube filled with a single liquid are compared with another model.     

Experimental study of a heat pump system with flash-tank coupled with scroll compressor

A heat pump system with a flash-tank coupled with a scroll compressor is compared with a system with a sub-cooler. The heat pump performance was measured experimentally. The heating capacity of the prototype decreased as the evaporation temperature decreased, but the decrease was much slower than that of a conventional air-source heat pump. The power input varied slightly with the evaporation temperature. The heat pump system with a flash-tank is more efficient than the system with a sub-cooler at low ambient temperatures, so it will be very useful as a small capacity air-source heat pump.     

含交叉多裂隙类岩石材料单轴压缩力学性能研究

 以类岩石材料模拟岩体,考虑了主次多裂隙、等长多裂隙两类交叉多裂隙形式,制作含交叉多裂隙试件,对试件进行单轴压缩实验,研究了含交叉多裂隙岩体在单轴压缩下的力学性能。研究表明：含2条交叉裂隙试件强度高于含单一裂隙试件,当裂隙数量超过2条(不含)时,含主次多裂隙试件峰值强度与含单一裂隙试件接近,含等长多裂隙试件的峰值强度及试件破坏所需外力功都低于含单一裂隙试件;次裂隙数量增加对含主次多裂隙试件强度影响不明显,裂隙数量增加对含等长多裂隙试件的强度降低作用非常明显;绝大部分含交叉多裂隙试件峰值强度对应应变低于含单一裂隙试件;含主次多裂隙试件起裂应力高于含单一裂隙试件,大部分含等长多裂隙试件起裂应力低于含单一裂隙试件;含单一裂隙试件破坏面为剪切裂隙,含交叉多裂隙试件破坏面以张拉裂隙为主。     

Plant fibre reinforced cement components for roofing

Composites of blast furnace slag (BFS) based cement mortar reinforced with vegetable fibres are presented. Roofing components are produced with these composites through a simple and low-energy consuming method, including ordinary vibration and curing in a wet chamber. Composites reinforced with eucalyptus pulp, coir fibres and with a mixture of sisal fibre and eucalyptus pulp gave a suitable performance, with compressive strength higher than 20 MPa and modulus of rupture (MOR) higher than 3 MPa. The performance of tiles made with these composites is in accordance with international requirements, with maximum load higher than 450 N, in wet conditions.     

Reinforcement of rock mass with cross-flaws using rock bolt

Rock bolting is one of the most effective and economical means of rock mass reinforcement. Existing studies of rock bolt reinforcement are mostly focused on rock masses without flaw, with a single flaw, or with parallel flaws. However in rock masses, cracks or flaws usually exist in the form of cross-flaws. In order to understand the impact of cross-flaws on rock bolt reinforcement and to further explore the differences of bolt reinforcement between rock mass with cross-flaws and rock mass with a single flaw, reinforced analog specimens with cross-flaws and with a single flaw were tested under uniaxial compressive condition. The experimental results show that the uniaxial compressive strength of the reinforced rock mass with cross-flaws in this research is higher than that of reinforced rock mass with a single flaw. This observation can be explained by the difference in the failure modes of reinforced specimens: the reinforced rock masses with a single flaw fail due to the formation of a shear crack while reinforced rock masses with cross-flaws fail as a result of a tensile fracture or interaction between tensile fracture and shear fracture.     

Simplified models for exhaled airflow from a cough with the mouth covered

Covering a cough can be useful in reducing the transmission of airborne infectious diseases. However, no simple method is available in the literature for predicting the exhaled airflow from a cough with the mouth covered. This investigation used smoke to visualize the airflow exhaled by 16 human subjects. Their mouths were covered by a tissue, a cupped hand, a fist, and an elbow with and without a sleeve. This study then developed simplified models for predicting the airflow on the basis of the smoke visualization data. In addition, this investigation performed numerical simulations to assess the influence of mouth coverings on the receptor's exposure to exhaled particles. It was found that covering a cough with a tissue, a cupped hand, or an elbow can significantly reduce the horizontal velocity and cause the particles to move upward with the thermal plumes generated by a human body. In contrast with an uncovered cough, a covered cough or a cough with the head turned away may prevent direct exposure.     

广安市明月渠江部分斜拉桥设计

广安市明月渠江特大桥为预应力混凝土部分斜拉桥，主桥跨径布置为（110+210+110）m，采用墩梁塔固结体系。主梁为单箱三室截面，宽度为23m，根部截面高度为7.5m，跨中截面高度为1.6m，梁体设三向预应力钢筋，采用悬臂浇筑法施工。主塔为钢筋混凝土结构，采用矩形截面，塔高32.05 m。斜拉索为单索面双排索，全桥共设置56 对索。索鞍采用分丝管式索鞍，索鞍塔壁两侧设置双向抗滑键。本文研究结果可为后续类似工程设计提供参考。     

Evaluation of the ground-coupled quasi-stationary heat transfer in buildings by means of an accurate and computationally efficient numerical approach and comparison with the ISO 13370 procedure

The purpose of this article is to present and validate a computationally efficient numerical approach for the calculation of the ground-coupled heat transfer in buildings with periodic boundary conditions. When the boundary conditions of the heat transfer problem are described by periodic functions, it is possible to consider the transient state problem as a quasi-stationary problem with considerable savings in terms of computational time. The method is presented in detail from a mathematical point of view, together with a validation for two simple cases of slab-on-grade thermal losses, four comparisons with the ISO 13370:2007 procedure, a case with a complex shape and an evaluation of the computational efficiency.     

挡土墙土压力非线性分布的计算方法研究

基于数学方法对斜单元体进行力和力矩的平衡分析, 得到了墙背粗糙且填土坡面倾斜情况下的土压力解析解, 并进一步分析了填土坡面倾角对土压力的影响。对比分析表明: 经典朗肯土压力理论可看作是解析解在墙背光滑、填土坡面水平情况下的特例; 在填土内摩擦角一定时, 挡土墙墙后滑动楔体的极限破裂角随着填土坡面倾角或墙土之间摩擦角的增大而减小。基于解析解得到的土压力分布呈现明显的非线性特征, 且在填土面水平情况下挡土墙墙脚处的土压力为0, 这与实测数据取得了很好的一致。分析还表明, 随着填土坡面倾角的增大, 墙脚处的土压     

Centrifuge model test on dynamic behavior of group-pile foundation With inclined piles and its numerical simulation

In this paper, dynamic behavior of a grouppile foundation with inclined piles in loose sand has been investigated with centrifuge model tests. The test results are also simulated with elastoplastic dynamic finite element method, in which, not only sectional force of piles, stress of ground, but also deformation of piles are calculated using a three-dimensional elastoplastic dynamic finite element analysis (Code name: DGPILE-3D). The numerical analyses are conducted with a full system in which a superstructure, a pile foundation and surrounding ground are considered together so that interaction between pile foundation and soils can be properly simulated because the nonlinearities of both the pile and the ground are described with suitable constitutive models. Different types of piles, vertical pile or inclined pile, are considered in order to verify the different characteristics of a group pile foundation with inclined piles. The validity of the calculation is verified by the model tests.