Competing rationalities and informal settlement upgrading in Cape Town, South Africa: a recipe for failure

The South African National Department of Housing’s ‘Breaking New Ground: A Comprehensive Plan for the Creation of Sustainable Human Settlements’ was released in 2004. This policy directive acknowledged that informal settlements had grown significantly since 1994. It resulted in the development and implementation of the informal settlement upgrading programme across the country. The principle objective of the study discussed in this paper was to investigate the City of Cape Town’s (the City) rationale in the technique of upgrading the informal settlements of Makhaza and New Rest in Cape Town and explore the implications of this rationale for women’s social networks in these two settlements. The research has found that the rationale used by the City to plan and implement the upgrading of informal settlements is contradictory to the needs of the residents within these settlements. The settlements therefore do not meet the needs of the residents (particularly women) and do not enable or ensure the maintenance of strong social relationships which are crucial for the survival of livelihoods in these areas.     

A comparative life cycle assessment of hybrid osmotic dilution desalination and established seawater desalination and wastewater reclamation processes

The purpose of this study was to determine the comparative environmental impacts of coupled seawater desalination and water reclamation using a novel hybrid system that consist of an osmotically driven membrane process and established membrane desalination technologies. A comparative life cycle assessment methodology was used to differentiate between a novel hybrid process consisting of forward osmosis (FO) operated in osmotic dilution (ODN) mode and seawater reverse osmosis (SWRO), and two other processes: a stand alone conventional SWRO desalination system, and a combined SWRO and dual barrier impaired water purification system consisting of nanofiltration followed by reverse osmosis. Each process was evaluated using ten baseline impact categories. It was demonstrated that from a life cycle perspective two hurdles exist to further development of the ODN-SWRO process: module design of FO membranes and cleaning intensity of the FO membranes. System optimization analysis revealed that doubling FO membrane packing density, tripling FO membrane permeability, and optimizing system operation, all of which are technically feasible at the time of this publication, could reduce the environmental impact of the hybrid ODN-SWRO process compared to SWRO by more than 25%; yet, novel hybrid nanofiltration-RO treatment of seawater and wastewater can achieve almost similar levels of environmental impact.     

Source apportionment of heavy metals and ionic contaminants in rainwater tanks in a subtropical urban area in Australia

Due to prolonged droughts in recent years, the use of rainwater tanks in urban areas has increased in Australia. In order to apportion sources of contribution to heavy metal and ionic contaminants in rainwater tanks in Brisbane, a subtropical urban area in Australia, monthly tank water samples (24 sites, 31 tanks) and concurrent bulk deposition samples (18 sites) were collected during mainly April 2007-March 2008. The samples were analysed for acid-soluble metals, soluble anions, total inorganic carbon and total organic carbon, and characteristics such as total solid and pH. The Positive Matrix Factorisation model, EPA PMF 3.0, was used to apportion sources of contribution to the contaminants. Four source factors were identified for the bulk deposition samples, including ‘crustal matter/sea salt’, ‘car exhausts/road side dust’, ‘industrial dust’ and ‘aged sea salt/secondary aerosols’. For the tank water samples, apart from these atmospheric deposition related factors which contributed in total to 65% of the total contaminant concentration on average, another six rainwater collection system related factors were identified, including ‘plumbing’, ‘building material’, ‘galvanizing’, ‘roofing’, ‘steel’ and ‘lead flashing/paint’ (contributing in total to 35% of the total concentration on average). The Australian Drinking Water Guideline for lead was exceeded in 15% of the tank water samples. The collection system related factors, in particular the ‘lead flashing/paint’ factor, contributed to 79% of the lead in the tank water samples on average. The concentration of lead in tank water was found to vary with various environmental and collection system factors, in particular the presence of lead flashing on the roof. The results also indicated the important role of sludge dynamics inside the tank on the quality of tank water.     

Onset of mucosal, dermal, and general symptoms in relation to biomarkers and exposures in the dwelling: a cohort study from 1992 to 2002

We examined the associations between biomarkers of allergy and inflammation, indoor environment in dwellings, and incidence and remission of symptoms included in the sick building syndrome (SBS) and changes in the home environment of 452 adults who were followed from 1992 to 2002 within the Uppsala part of the European Community Respiratory Health Survey (ECRHS). The 10-year incidence (onset) of general, mucosal, and dermal symptoms was 8.5%, 12.7%, and 6.8%, respectively. Dampness or indoor molds at baseline was a predictor of incidence of general (relative risk [RR] = 1.98), mucosal (RR = 2.28), and dermal symptoms (RR = 1.91). Women had higher incidence of general (RR = 1.74) and mucosal symptoms (RR = 1.71). Indoor painting increased the incidence of general symptoms (RR = 1.62). Bronchial responsiveness (BR), eosinophil counts in blood, total IgE and eosinophilic cationic protein (ECP) in serum at baseline were predictors of incidence of SBS. At follow-up, BR, total IgE, and C-reactive protein (CRP ) were associated with increased incidence of SBS. Moreover, subjects with doctor-diagnosed asthma at baseline had a higher incidence of general (RR = 1.65) and mucosal symptoms (RR = 1.97). In conclusion, female gender, dampness or indoor molds, indoor painting, and biomarkers of allergy and inflammation were associated with a higher incidence of SBS symptoms, in particular mucosal symptoms. PRACTICAL IMPLICATIONS: The focus in Sweden on indoor environment issues over the last few decades has resulted in improvements in dwellings, and reduced tobacco smoking, which could be beneficial for public health. Reducing dampness and molds in the dwelling place is another important way of reducing occurrence of SBS symptoms in the general adult population. The association between the incidence of SBS symptoms and clinical biomarkers of allergy and inflammation suggests a common etiology between inflammatory diseases, including asthma, rhinitis, and SBS. Lastly, good agreement between self-reported and clinically diagnosed atopy indicates that questionnaire data on atopy can be used in epidemiological studies.     

Use of Spreadsheets as an Introductory Tool for Solving Fluid-Structure Interaction Problem

A simple and intuitive manner for solving fluid-structure interaction problem has been developed using Microsoft Excel spreadsheets. By eliminating the need of previous knowledge of any programming language, the method appears as an interesting introduction to numerical solutions of partial differential equations, due to the direct and didactic way that it is developed. Proposed procedure enables the analysis of tridimensional geometries using the finite difference method and can be extended to other differential equations or boundary conditions. The author＇s objective in this paper is to develop a simple and reliable preliminary method for solving acoustic fluid-structure interaction problems with application to dam-reservoir interaction phenomena and also contribute in the educational growth for undergraduate students that are beginning research in such matter.     

Structural Response of World Trade Center Buildings 1, 2 and 7 to Impact and Fire Damage

The National Institute of Standards and Technology (NIST) conducted an extensive investigation of the collapse of World Trade Center towers (WTC 1 and WTC 2) and the WTC 7 building. This paper describes the component, subsystem, and global analyses performed for the reconstruction of the structural response of WTC buildings 1, 2, and 7 to impact and fire damage. To illustrate the component and subsystem analyses, the approach taken for simulating the performance of concrete slabs and shear stud connectors in composite floors subject to fire conditions are presented, as well as steel floor framing connections for beams and girders. The development of the global models from the component and subsystem analyses is briefly described, including the sets of input data used to bound the probable conditions of impact and fire damage. The final analysis results that were used to develop the probable collapse hypotheses, and a comparison of the results against observed events, are presented for each building. A review of research activities focused on improving understanding of structural system response to multi-floor fires following the WTC disaster is also provided.     

The need to control asbestos fibers in potable water supply systems

Occupational studies have shown that asbestos is a human carcinogen. Becausemany inhaled asbestos fibers deposited in the lung are cleared and swalloed workers are also exposed through ingestion. Of the millions of current and former workers who have been heavily exposed to asbestos, one in ten will die from cancer of the gastrointestinal tract. A number on the order of 1 in 1,000 ingested asbestos fibers penetrate the digestive tract and ingested fibers have been recovered in such tissues as kidney, intestine, liver, and urine. One animal study showed tumor production related to ingestion of asbestos-containing material but, in general, the results of seven animal feeding studies have been inconclusive. A statistically significant relationship between male lung and stomach cancer and female peritoneal, gall bladder, and esophageal cancer and asbestos counts in drinking water was determined in one epidemiology study. Increased rates for male stomach and lung, and female pancreatic cancer related to asbestos in drinking water were reported in another study but possible occupational exposure made it difficult to draw conclusions. Data on excess gastrointestinal cancer among occupational groups has been used to estimate that drinking water containing 300,000 asbestos fibers per liter over a lifetime will result in one additional cancer among 100,000 people.     

The control of potential health Risks related to drinking water in the UK

In the United Kingdom, potable water put into supply is required to be‘wholesome’ The term ‘wholesome’ is interpreted as clear, palatable and safe to drink. About 99% of potable supplies are provided by Regional Water Authorities and Water Companies (for England and Wales), Regional Councils and Island Councils (for Scotland) and the Department of the Environment (NI) (for Northern Ireland). Those water authorities draw their raw water from upland surface waters, lowland surface waters (including lakes and rivers) and underground waters. Although each source provides approximately one-third, of supply, the proportion varies considerably in different parts of the UK. Consequently the control of potential health risks related to drinking water also varies according to the source of supply. The paper describes briefly the treatment practice for the various sources, including disinfection practice. More specifically the paper describes current UK practice or developments in the control or investigation of plumbosolvency, fluoridation, nitrate, trihalomethanes, other organic micropollutants, sodium, asbestos and tar linings in pipes. The possibilities for the surveillance of the 1% of private supplies are also discussed.     

High-resolution CFD simulations for forced convective heat transfer coefficients at the facade of a low-rise building

High-resolution 3D steady RANS CFD simulations of forced convective heat transfer at the facades of a low-rise cubic (10 × 10 × 10 m³) building are performed to determine convective heat transfer coefficients (CHTC). The focus is on the windward facade. CFD validation is performed based on wind tunnel measurements of velocity and heat transfer for reduced-scale cubic models. The CFD simulations employ a high-resolution grid with, for the 10 m cubic building, cell centres at a minimum distance of 160 μm from the building surface to resolve the entire boundary layer, including the viscous sublayer and the buffer layer, which dominate the convective surface resistance. The results show that: (1) the wind flow around the building results in highly varying CHTC values across the windward facade; (2) standard and non-equilibrium wall functions are not suitable for CHTC calculation, necessitating either low-Reynolds number modelling or specially-adapted wall functions; (3) at every facade position, the CHTC is a power-law function of the mean wind speed; (4) the CHTC distribution at the windward facade is relatively insensitive to wind direction variations in the 0–67.5° angle range; (5) the CHTC shows a stronger spatial correlation with the turbulent kinetic energy than with the mean wind speed across the facade; and (6) the CHTC distribution across the windward facade is quite similar to the distribution of wind-driven rain (WDR), with both parameters reaching high levels near the top edge of the facade. This suggests that also the convective moisture transfer coefficient will be higher at this location and that the facade parts that receive most WDR might also experience a higher drying rate.     

钢管混凝土柱螺栓连接钢梁节点的抗震性能分析

为了改进施工过程,同时确保房屋的抗震性能,提出了一种新型的连接类型,用于钢管混凝土柱和钢梁的连接处设计。该连接具有外伸端板的特性,出厂前与钢梁焊接在一起,然后在现场用高强钢将其与钢管混凝土柱螺栓连接。对这种螺栓连接端板节点的抗震性能进行试验研究,并通过对3个足尺节点模型进行试验,评估了混凝土楼板和削弱型梁截面对其的影响。试验结果表明:楼板对节点强度的作用显著,削弱型梁截面能有效地将屈曲区域转移到远离焊接点的位置。同时,螺栓连接端板节点的分析模型也采用OPENSEES1.7.3模拟了试验结果。