58 research outputs found
Connecting the dots in infrastructure development and management: The Africa agenda for new innovation
It is widely accepted that the growth and prosperity of nations is dependent on economic
infrastructure. Infrastructure is constituted by cyber-physical systems that enable
communications (e.g. postal, telephone and internet) as well as transportation (e.g. road,
water, air), energy (e.g. electricity and gas) and other utilities (e.g. drinking water and waste)
(Chandler, 1977; NAO, 2013). It provides the basis for economic growth and prosperity
through the provision of essential services that enable economic and social activity. As a
result, it delivers significant benefits, both directly through the services it delivers, and
indirectly through the impact of those services on the rest of the economy (Nightingale et al
2016). However, these benefits come at a cost. Infrastructure is expensive to build, operate
and maintain. The provision of infrastructure involves degradation and the consumption of
natural ecosystems, displacement of local communities, CO_{2} emissions, noise and pollution.
Infrastructure is typically long-lived and the costs of poor choices and mistakes can affect
future generations. This is especially prominent with politically motivated infrastructure
investment decisions, which have a lifespan that coincides with electoral cycles. To
complicate matters further, the costs and benefits of infrastructure provision fall unequally
across society in a way that benefits a minority (usually local to the area of infrastructure
development) although the distribution of costs are more widely spread (for example in
investments funded by taxes) (ibid). In this context, infrastructure investment decisions are
not only complex they are inherently political
A new height datum for Iran based on the combination of gravimetric and geometric geoid models
A new geoid model for Iran (IRG04) was computed based on the least squares modification of the Stokes formula. IRG04 was derived from the most recent gravity anomaly database, SRTM high resolution Digital Elevation Model (DEM) and GRACE GGM02 global geopotential model. In order to define a new height datum for Iran, we attempted to combine this high resolution gravimetric geoid model with GPS/levelling data using the corrective surface approach. The corrective surface was constructed from 224 GPS/levelling points and then evaluated with 35 independent points. Different interpolation techniques were tested for the creation of the corrective surface; among them the Kriging method was selected as it gave the smallest RMS and ‘noise level’ at the comparisons with GPS/levelling data. The RMS fit of the new combined geoid model versus the independent GPS/levelling data is 0.09 m, it is near four times better compared to the original gravimetric geoid model. The combined model should be more convenient and useful in definition of the new height reference surface, specifically in engineering and GPS/levelling projects
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