充气梁的有限元分析

采用包括Timoshenko动力学、有限转动和小应变的虚功原理定义充气梁弯曲和屈曲的离散非线性计算公式。随后推导出预应力参考构型的线性计算公式,从而得出新的充气梁有限元分析方法。刚度矩阵包括剪切系数和内压力。采用三节点梁单元建模分析悬臂梁的弯曲和屈曲、带箍环面的变形以及承受放射状压力的环面屈曲。采用这种梁元计算的结果与采用三维膜单元有限元计算结果很相近。结合充气梁的冲撞力或者蠕变压力概念,讨论了数值计算结果的有效性。     

Informal Sector Business Tourism in the Global South: Evidence from Maseru, Lesotho

Domestic tourism is a neglected theme within tourism scholarship about the global South. This article addresses informal sector domestic tourism and is anchored upon the typology of tourism by Gladstone (2005) in which distinctions are drawn between international and domestic tourism and formal and informal sector tourism. The specific focus is informal sector business tourism, the nature of which challenges Western definitions of business tourism. The study reports findings from 52 interviews conducted with informal business tourists and accommodation providers in Maseru, Lesotho’s capital city. It is revealed the nature of low-income informal sector business tourism in the global South is radically different to that of conventional business tourism in terms of its organisation, characteristics of business tourists, and impacts. Arguably, informal sector business tourism is inherently pro-poor in its local impacts. Further comparative research work is required concerning these forms of ‘invisible’ tourists in African cities.     

Comparative performance of healthcare and transport PFI projects: Empirical study on the influence of key factors

Private Finance Initiative (PFI) has been used on many projects in the UK in the delivery of public services. Cost, time and risk performance in public projects was anticipated to be improved by the superior skills of the private sector. So far, there are limited empirical studies on the life cycle performance of PFI projects, especially performance comparison between different sectors. This study investigated and compared variations in costs, time, and client requirements tracking it through the strategic business case stage to the operational phase in healthcare and transport sectors. It explored the influence of sector-specific factors, project size and maturity of the PFI on these variations. It used documentary analysis of full business cases of five PFI projects and a questionnaire survey of 44 PFI projects in the UK. The findings reveal that there are still considerable cost and time overruns and requirement changes in PFI projects in both sectors over the development of the project and its early use. The health sector was better than the transport sector for time overruns but was worse on costs. Smaller-value projects outperformed larger projects on cost variations but underperformed on time.     

Comparison of coagulation performance and floc properties using a novel zirconium coagulant against traditional ferric and alum coagulants

Coagulation in drinking water treatment has relied upon iron (Fe) and aluminium (Al) salts throughout the last century to provide the bulk removal of contaminants from source waters containing natural organic matter (NOM). However, there is now a need for improved treatment of these waters as their quality deteriorates and water quality standards become more difficult to achieve. Alternative coagulant chemicals offer a simple and inexpensive way of doing this. In this work a novel zirconium (Zr) coagulant was compared against traditional Fe and Al coagulants. The Zr coagulant was able to provide between 46 and 150% lower dissolved organic carbon (DOC) residual in comparison to the best traditional coagulant (Fe). In addition floc properties were significantly improved with larger and stronger flocs forming when the Zr coagulant was used with the median floc sizes being 930 μm for Zr; 710 μm for Fe and 450 μm for Al. In pilot scale experiments, a similar improved NOM and particle removal was observed. The results show that when optimised for combined DOC removal and low residual turbidity, the Zr coagulant out-performed the other coagulants tested at both bench and pilot scale.     

Effect of flow rate and lead/copper pipe sequence on lead release from service lines

A pilot experiment examined lead leaching from four representative configurations of service lines including: (1) 100% lead (Pb), (2) 100% copper (Cu), (3) 50% Pb upstream of 50% Cu, and (4) 50% Pb-downstream of 50% Cu using a range of flow rates. The cumulative mass of lead release indicated that a typical partial replacement configuration (50% lead downstream of copper) did not provide a net reduction in lead when compared to 100% lead pipe (85 mg for 50% Pb-downstream versus 83 mg for 100%-Pb) due to galvanic and deposition corrosion. The partially replaced service line configuration also had a much greater likelihood of producing water with "spikes" of lead particulates at higher flow rates, while tending to produce lower levels of lead at very low flow rates. After the first 214 days the galvanic current between copper and lead was only reduced by 34%, proving that galvanic impacts can be highly persistent even in water with optimized corrosion control by dosing of zinc orthophosphate. Finally, this experiment raises concern about the low flow rates used during some prior home sampling events, which may underestimate exposure to lead during normal water use, especially when galvanic Pb:Cu connections are present.     

Transfer of Ultrafine Particles and Air in Multi-storey Buildings

An emerging issue in Denmark is passive smoking in residential buildings where non-smokers are exposed to smoke from their neighbours. There are various ways that smoke is transferred from one flat to another. The air transfer rate between two flats in a multi-storey building depends on its construction, tightness and age. This paper presents results of a study on the transfer of ultrafine particles and tracer gas in an older multi-storey building in Copenhagen. The aim of the study was to quantify the transfer ofultrafine particles and gases from one flat to another fiat before and after sealing the floor. A new floor-sealing method was applied to seal the floor between the two flats. The sealing method was developed by a firm specialising in sealing. Indoor ultrafine particle concentrations and tracer gas were measured continuously in the two fiats during the measuring periods. In the unoccupied fiat, the gas source was N20 and the particle source was burning cigarettes. Reduction of the concentration of ultrafine particles and tracer gas by sealing the floor with polyethylene and joint filler made of bitumen was studied. It was evaluated how the sealing performed with regard to decreasing the amount of ultrafine particles and a tracer gas transferred between two fiats separated by a floor. When the floor between the flats was not sealed, the results showed that about 4% of the ultraflne particles and 14% of the tracer gas were transferred. After sealing, the amount transferred was reduced to 1.6% and 5%, respectively.     

Les glissements de terrain du quartier Bélouizdad, Constantine, Algérie

In Constantine, Belouizdad district landslides are extensive (Fig. 1). They occur along a hillside largely urbanized, and cover over 30 hectares. Dozens of houses were destroyed. The formations raised by these movements correspond to the alternating of thick Miocene clays and conglomerates. These contain several aquifers. The study of these landslides is conducted on the basis of recognition by deep boreholes equipped with piezometers and inclinometers. The inclinometric measurements have revealed failure surfaces sometimes deep (20 to 30 m) and north displacement, towards the Rhumel wadi. The use of a stability calculation software “Talren” shows on the one hand, the high sensitivity of unstable Miocene formations in the presence of water and on the other hand, a significant revival of the safety factor by reducing the pore pressure. The recommended solutions are therefore a lowering of underground water levels. Two techniques are recommended : deep drainage trench or galleries combined with radiating drainage holes.     

Special Economic Zones in South Africa: Reflections from International Debates

South Africa’s experience with spatial economic interventions has had a chequered history with the Industrial Development Zone programme most recently failing to generate anticipated development. Current policy has shifted to the imminent launch of Special Economic Zones (SEZs) as tools for national (re)industrial development and supporting underdeveloped regions. This paper reflects on recent South African experience with spatial economic interventions and international experience with SEZs paying particular attention to their strengths, weakness and key establishment considerations. It is argued that unfolding South African SEZ planning can be strengthened by learning from the ‘good’ and ‘bad practice’ of international SEZs.     

Scharnhauser公园学校和体育馆,奥斯特菲尔登

这个综合学校包括一个主建筑,一个体育馆和各种户外设施,朝向一片处在前军事基地上的住宅开发区。整个主建筑沿纵向被一个由顶部采光的回廊从中间分开,由此可以进入两侧的教室,回廊局部变宽的部分构成一个公共空间。这个构想与将城市设计理论运用于建筑内部设计的概念相符合:街道、广场和建筑被看成了建筑内部空间部分。虽然这个建筑从外部看来是个大体块,但内部空间却设计流畅,通道有的通向楼层的各个角落,也有的依着倾斜的地势因势而建。由墙面反射的散射光线加强了内部空间的肃穆和厚重感。在具有宗教感的整体风格下,整个学校的设计和装饰也显得古香古色,如一部宽阔的观光楼梯、两个塔形和壁炉形的建筑构成元素等。不同历史风格建筑的叠加给这个校区带来一种复杂的味道,堪比阿尔多·罗西(Aldo Rossi)的设计或泰辛(Tessin)新理性主义的代表作。     

从整体的地景综合到跨学科的地景管理

"地景"一词的内涵是很丰富的,且这个概念本身即蕴含着一种固有的整体观。早在文艺复兴时期,欧洲就已经产生了若干种相异的安排和布置地景的方式,不同的方式运用着不同的观念和方法。我们可以将其划分为三类,第一是自然科学,其中地景生态学起着主导作用;第二是人文科学,其中多运用历史地理、历史生态学、人文主义和符号学等手法的途径;第三是应用科学,主要是指地景设计、建筑设计与规划领域。每一分类都有助于人们深入理解地景。本文对不同类别的地景研究进行比较,但直到目前它们也还没有形成共同的观念、相同的目标和统一的描述语言,至于如何在"跨学科"的地景科学的框架下实现具有创造力的综合创新也就更无法明确。但必须明确的是,对于地景,无论是管理还是规划,我们面对的都是一块相同的土地,是面对同一对象来解决各种各样的问题。那么,这个过程就必须采取综合的方法,就不可避免地要进行跨学科的合作。