CMC和PAM对砂浆性能的影响

加气混凝土是一种新型建筑材料，自身具有许多优点。然而由于普通砂浆的保水性能不能适应加气混凝土的吸水性能，加气混凝土抹灰层经常出现开裂现象，这阻碍了加气混凝土的广泛应用。通过两类增稠剂CMC和PAM）对砂浆性能影响的试验研究发现，CMC可以大幅度提高砂浆的保水性能，从而可以较好地解决普通砂浆的保水性能与加气混凝土吸水性能不相适应的问题：PAM对普通砂浆的保水性能改善较少。     

多病床非典病房的气流分布研究

到2003年8月7日止，在全球34个国家和地区相继出现了严重急性呼吸系统综合症(SARS或者非典)，其中，共报告有8422例疑似案例，916例死亡案例。2002年11月到2003年6月间的非典流行中，医院医护人员受感染情况最为严重，世界范围内20％的感染群体为医护人员，香港地区22％的确诊案例为医护人员。因此，为减少交叉感染，加强有关工程控制，特别是在非典病房里进行通风设计是非常必要的。本文总结了非典病房气流分布的最新研究。这项研究由非典特工队于2003年4～7月间完成。非典特工队是由香港工程师协会组织，来自7个专家协会的工程师组成的研究小组。在对香港治疗非典医院的现有空调系统进行了解后，非典特工队首先运用计算流体力学模拟确定了在6个床位的病房里减少交叉感染和改善污染物稀释的通风设计；接着，对新设计在香港大学屋宇设备实验室里的全尺寸非典病房里进行了测试。测试表明，新设计方案在这个接近现实的全尺寸非典病房里运行良好。采用床头回风口回风设计可有效地对病人产生的含病毒颗粒进行局部捕获。根据这项研究，作者提出了原则性的设计建议。2003年里，香港政府和医院管理局医院采纳了非典特工队提出的设计基本原理建造了1200多个床位的可用于非典治疗的新病房。另外，气流分布是复杂的紊流过程，送风格栅结构如导流器或散流器的微小改动以及送风参数如风速、温度和风向的微小变化都会引起气流的改变。适当的设计对于减少病人间、病人与医护人员之间的交叉感染以及有效稀释和排除含病菌颗粒都是至关重要的。     

砖混结构房屋顶层温度缝的原因分析及防治

本文从设计和施工两个方面分析了砖混结构房屋顶层常出现温度缝的原因,并提出了具体的防治措施和加固方案,为解决这一工程质量通病提供了依据。     

Elastic-viscoplastic finite-element analysis of a forging die

The elastic-viscoplastic constitutive equations of Bodner-Partom have been implemented in a nonlinear finite-element computer program. Using the modified program, a series of computer simulations of a bottom die in a hot-die forging operation has been performed. The results demonstrate that the elastic-viscoplastic finite-element program is particularly suited for high-temperature structural-analysis applications for components which are subjected to complex arbitrary deformation and thermal histories such as those encountered by a forging die or workpiece. In addition, these simulations establish the local stress and strain values at various critical locations, the displacements of the die surface, and the critical loads for potential failure of the forging die.     

Effect of refraction on optical microscopic measurement of internal blood-vessel diameter and its correction

In optical microscopic measurement of internal blood-vessel diameters, the effect of refraction must be taken into account to ensure accuracy of the result. This effect is discussed and an analytical correction formula derived. Phantom blood vessels with known internal and external diameters were used to test the validity of the correction formula. The errors obtained prior to correction were reduced significantly after correction.     

A framework for identification and representation of client requirements in the briefing process

The briefing process is critical to the successful delivery of construction projects. Although a number of briefing guides have been developed, attempting to address the problems of briefing, they are often criticized as being too general and implicit. This paper describes a structured framework for identifying and representing client requirements (CRs) in the briefing process. It integrates the value management (VM) methodology with function analysis system technique (FAST) and functional performance specification (FPS) to enable the client organization and project team to systematically identify, clarify and clearly represent CRs in the briefing process. It comprises four interrelated phases: preparation, information, analysis and evaluation. This paper starts with a critical review of previous work in briefing and function analysis, followed by an introduction to the research methodology and detailed illustration of the proposed framework. The use of this framework can facilitate and lead to systematic identification and clarification of client requirements and the formation of a more precise and explicit representation of these requirements. The limitations of the approach are also discussed in the paper.     

Mechanism and feasibility of colloidal particle removal by a microcarrier process

Pollutants associated with colloidal particles in stormwater runoff have received increasing attention. Removal of these toxic particles is of paramount importance in regulating the quality of stormwater effluents. With the promulgation of the USEPA's Enhanced Surface Water Treatment Rule, a means for the removal of these particles in an efficient and rapid manner in treatment facilities is needed. This paper reviews the mechanisms and feasibility of a high rate sedimentation process in enhancing the settling in the flocculation‐sedimentation approach. The advantages of microcarriers, namely, to enhance particle capture as well as rapid sedimentation, are presented. A series of microcarrier‐jar tests was carried out. The experimental results reveal that the microcarrier process is effective in dramatically reducing treatment time and, in turn, reducing the size of treatment facility needed in a standard coagulation/flocculation unit operation.     

Genetic algorithm optimization in building portfolio management

A significant proportion of building investment expenditure goes to replacement expenditure for organizations owning a large building stock or portfolio. Over the years, researchers have attempted to develop asset replacement models to aid decision-making in building portfolio management, based upon' a statistical or an heuristic approach. This study attempts to use genetic algorithms to develop models for forecasting long term asset replacement strategies, aiming at smoothing fluctuations of expenditure and resource requirements, and most importantly minimizing the total maintenance and replacement costs. Scenarios are presented to demonstrate how these can be achieved. Further refinement for practical application of the models is also presented.     

Respiratory bioaerosol deposition from a cough and recovery of viable viruses on nearby seats in a cabin environment

Respiratory bioaerosol deposition in public transport cabins is critical for risk analysis and control of contact transmission. In this work, we built a two-row four-seat setup and an air duct system to simulate a cabin environment. A thermal manikin on the rear left-hand seat was taken as the infected passenger (IP) and “coughed” three times through a cough generator. The deposited viruses and droplets on nearby seats were measured by a cultivation method and microscope, respectively. The effects of seat backrest and overhead gasper jet were studied. Results showed that the number of deposited virus on the front seat was one order of magnitude higher than that on other seats which only contained droplets smaller than 10 µm in diameter. When the backrest was 15 cm higher than the cough, the deposited number of viruses was reduced to 5% of that with the backrest at the same height with the cough. The gasper jet above the IP with a velocity of 1.5 m/s can reduce the deposited viruses to 4% of that with gasper off. It indicates that both the gasper jet and backrest can work as mitigation measures to block the cough jet and protect the nearby passengers.