67 research outputs found
Spatial knowledge management and participatory governance: rethinking the trajectories of urban, socio-economic and environmental change and the politics of 'sustainability' in southern cities
This paper presents the analytical framework developed iteratively by the research team of the Chance2Sustain (C2S) research project between 2010 and July 2014, in order to answer the main research question which was posed at the outset of the research, namely : how can spatial knowledge management (SKM) and participatory governance contribute to sustainable urban development ? To answer this question, the C2S project was designed to undertake comparative empirical research in 10 cities in four fast-growing countries of the South to understand the role of SKM and participatory processes in facing the challenges in a number of strategic domains of urban development ; those of economic growth, social inequality and vulnerability, and environmental governance. In each city, there were researchers from both the North and South working together in the five domains of economic growth through megaprojects ; social mobilisation and social exclusion in sub-standard settlements ; environmental governance with the focus on water-related issues ; spatial knowledge management; and fiscal decentralisation and participatory city budgeting
Vibrational dynamics of confined granular material
By means of two-dimensional contact dynamics simulations, we analyze the
vibrational dynamics of a confined granular layer in response to harmonic
forcing. We use irregular polygonal grains allowing for strong variability of
solid fraction. The system involves a jammed state separating passive (loading)
and active (unloading) states. We show that an approximate expression of the
packing resistance force as a function of the displacement of the free
retaining wall from the jamming position provides a good description of the
dynamics. We study in detail the scaling of displacements and velocities with
loading parameters. In particular, we find that, for a wide range of
frequencies, the data collapse by scaling the displacements with the inverse
square of frequency, the inverse of the force amplitude and the square of
gravity. Interestingly, compaction occurs during the extension of the packing,
followed by decompaction in the contraction phase. We show that the mean
compaction rate increases linearly with frequency up to a characteristic
frequency and then it declines in inverse proportion to frequency. The
characteristic frequency is interpreted in terms of the time required for the
relaxation of the packing through collective grain rearrangements between two
equilibrium states
Short-time dynamics of a packing of polyhedral grains under horizontal vibrations
We analyze the dynamics of a 3D granular packing composed of particles of
irregular polyhedral shape confined inside a rectangular box with a retaining
wall sub jected to horizontal harmonic forcing. The simulations are performed
by means of the contact dynamics method for a broad set of loading parameters.
We explore the vibrational dynamics of the packing, the evolution of solid
fraction and the scaling of dy- namics with the loading parameters. We show
that the motion of the retaining wall is strongly anharmonic as a result of
jamming and grain rearrangements. It is found that the mean particle
displacement scales with inverse square of frequency, the inverse of the force
amplitude and the square of gravity. The short- time compaction rate grows in
proportion to frequency up to a characteristic frequency, corresponding to
collective particle rearrangements between equilibrium states, and then it
declines in inverse proportion to frequency
Force transmission in a packing of pentagonal particles
We perform a detailed analysis of the contact force network in a dense
confined packing of pentagonal particles simulated by means of the contact
dynamics method. The effect of particle shape is evidenced by comparing the
data from pentagon packing and from a packing with identical characteristics
except for the circular shape of the particles. A counterintuitive finding of
this work is that, under steady shearing, the pentagon packing develops a lower
structural anisotropy than the disk packing. We show that this weakness is
compensated by a higher force anisotropy, leading to enhanced shear strength of
the pentagon packing. We revisit "strong" and "weak" force networks in the
pentagon packing, but our simulation data provide also evidence for a large
class of "very weak" forces carried mainly by vertex-to-edge contacts. The
strong force chains are mostly composed of edge-to-edge contacts with a marked
zig-zag aspect and a decreasing exponential probability distribution as in a
disk packing
Mobility and the city improvement district: Frictions in the human-capital mobile assemblage
In this paper, we interrogate the role of the city improvement district (CID) in the
intervention and management of mobility within the context of the South African city and the
case study of the Groote Schuur Community Improvement District (GSCID), a public–private
urban governance scheme situated in Cape Town’s middle income southern suburbs. Using the
theoretical lens of bodily-scale mobility, we investigate the CID’s activation and management.
This is useful, as we will demonstrate, because it is through the mobility and immobility at the
scale of the body, where the CID’s mandate is operationalised and it is through the control of
mobility that the CID’s mission, discourses and activities are linked. This work demonstrates
that CIDs, as elite-driven urban renewal initiatives closely aligned with capital interests,
employ exclusionary spatial practices that have the potential to shape the twenty-first century
urban experience in significant ways. We conclude by theorising the co-constitutive nature of
human mobilities and capital as the ‘human-capital mobile assemblage’ and by arguing that
the CID occupies an ambivalent place in the contemporary city.IS
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