Influence of thermal effects on street canyon circulations

A numerical study has been carried out to investigate the influence of large-scale thermal effects and strong local-scale temperature gradients near the ground on the circulation inside a street canyon. The results show that the dynamical forcing dominates the circulation inside a street canyon. But this forcing is influenced by the large-scale thermal stability. Thus, atmospheric stability indirectly controls the street canyon circulation. Small temperature gradients inside the street-canyon are neutralised by the external dynamical forcing. Strong temperature gradients inside the street-canyon show an impact on the street canyon circulation. While stable stratification reduces the circulation for the building configuration investigated, convective stratification seems to intensify it.

Poverty, HIV, and barriers to education: street children's experiences in Tanzania

This article discusses the links between poverty, HIV/AIDS, and barriers to education, based on the first-hand experiences of ‘street children’ in northern Tanzania. Within the context of national levels of poverty, ‘cost-sharing’ in health and education sectors, and the AIDS epidemic, poor families in Tanzania are under considerable pressure, and increasing numbers of girls and boys are consequently seeking a living independently on the streets of towns and cities. My research with street children shows that some children orphaned by AIDS are subject to rejection and exploitation by the extended family after the death of their parent(s). They are exposed to considerable risks of abuse, sexual violence and HIV within the street environment. Here, I discuss the links between poverty, HIV and barriers to education, which compound young people’s vulnerability, and offer some policy recommendations in response to the young people’s experiences.

Start where you are: Graphic ordering influences improvisational dance

This article is an analysis and reflection on the role of lists and diagrams in Start where you are, a multimedia improvisational piece performed as part of square zero independent dance festival: the second edition/la deuxième édition. This interdisciplinary festival was organised by collective (gulp) dance projects and took place in Ottawa, Canada, in August 2005. Start where you are was the result of a collaboration between the authors: two dance artists (Andrew and MacKinnon, the principals of (gulp)) and a visual communication designer (Gillieson). A sound artist and a lighting technician also participated in the work. This is a post-performance retrospective meant to analyze more closely the experience that meshed the evidentiary weight of words and graphics with the ephemerality and subjectivity of movement-based live performance. It contextualizes some of the work of collective (gulp) within a larger tradition of improvisation in modern dance. It also looks at how choice-making processes are central to improvisation, how they relate to Start, and how linguistic material can intersect with and support improvisational performance. Lastly, it examines some characteristics of lists and diagrams, unique forms of visual language that are potentially rich sources of material for improvisation.

Negotiating social identities: the influence of gender, age and ethnicity on young people’s ‘Street Careers’ in Tanzania

This paper explores the diverse ways that children and young people negotiate their social identities and construct their life course trajectories on the street, based on ethnographic research with street children in Tanzania. Drawing on the concept of a ‘street career’, I show how differences of age, gender and ethnicity intersect with the time spent on the street, to influence young people’s livelihood strategies, use of public space, access to services, and adherence to cultural rites of passage. Using the notion of ‘gender performativity’, I analyse how young people actively reconfigure gender norms and the concept of ‘the family’ on the street.

Ventilation in a street canyon under diurnal heating conditions

To study the thermal effects on airflow in a street canyon under real heating conditions (due to diurnal solar radiation), a one-way static approach combining an urban canopy model and CFD is proposed in this paper. An urban canopy model was developed to calculate the individual temperatures of surfaces in the street canyon. The calculated surface temperature may be used as a thermal boundary for CFD simulation. The reliability of this model was validated against a field experiment in Harbin, China. Using the coupling calculation method, the wind flow and air exchange process inside an idealized street canyon was studied. The simulation results show that the thermal effect has significant impacts on the transfer process in the street canyon, especially when the approaching wind is weak. Under a real diurnal thermal forcing, the flow structure within the street canyon changes from one primary vortex to two counter-rotating vortices. The change of transfer process, induced by the buoyancy force, was determined by the thermal condition of all surfaces rather than a single one. Key words: thermal effect, street canyon, numerical simulation, transfer process, diurnal heating.