11,273 research outputs found
From Iconic Design to Lost Luggage: Innovation at Heathrow Terminal 5
This paper aims to contribute to understanding of how organizations respond to risk and uncertainty by combining and balancing routines and innovation. It shows how approaches to risk and uncertainty are shaped by the contractual framework in large multi-party projects. The paper addresses a gap in the literature on how risk and uncertainty is managed to deliver innovation in large-scale âmegaprojectsâ. These megaprojects are notorious for high rates of failure that conventionally evoke organizational strategies avoiding risks and uncertainties. Yet strategies for managing risk and uncertainty are essential to the routines and innovation that overcome the challenges of successfully delivering large-scale, complex projects.
The ultimate outcome of black hole - neutron star mergers
We present a simple, semi--analytical description for the final stages of
mergers of black hole (BH) -- neutron star (NS) systems. Such systems are of
much interest as gravitational wave sources and gamma--ray burst progenitors.
Numerical studies show that in general the neutron star is not disrupted at the
first phase of mass transfer. Instead, what remains of the neutron star is left
on a wider, eccentric, orbit. We consider the evolution of such systems as they
lose angular momentum via gravitational radiation and come into contact for
further phases of mass transfer. During each mass transfer event the neutron
star mass is reduced until a critical value where mass loss leads to a rapid
increase in the stellar radius. At this point Roche lobe overflow shreds what
remains of the neutron star, most of the mass forming a disc around the black
hole. Such a disc may be massive enough to power a gamma--ray burst. The mass
of the neutron star at the time of disruption (and therefore the disc mass) is
largely independent of the initial masses of the black hole and neutron star,
indicating that BH--NS star mergers may be standard candles.Comment: MNRAS, in pres
Crashworthiness of composite sandwich structures
Imperial Users onl
Ballistic missile defence: how soon, how significant, and what should Australia's policy be?
Summary: The issue of ballistic missile defence (BMD) was a controversial one when US President Reagan first advocated a strategic-level system in the early 1980s. It remains so today.
Whatâs Australiaâs interest? We live a long way away from most current ballistic missile arsenals. But the ADF frequently deploys within range of ballistic missile systems, especially in Northeast Asia or the Middle East, and those systems might proliferate more widely in the future.
The paper considers the two questions we need to decide. The first is the priority for enhancing the ADFâs own BMD capabilities. The second is whether it makes sense for us to participate in a cooperative arrangement with the US or other partners
How to buy a submarine: part 2
This paper describes some of the approaches that could be taken to replace Australia\u27s Collins class submarines and outlines their pros and cons.
Executive summary
The building of a replacement for Australia\u27s Collins class submarines will be the country\u27s most expensive defence project to date. It\u27s also likely to be the most complex, with a myriad of capability, commercial and industrial issues to be managed: the expertise for the design and construction of conventional submarines resides in Europe and Asia while Navy\u27s preference is for American combat and weapon systems. Pulling those elements together while managing the technical risks is no easy task.
Local construction of the future submarine has been a bipartisan position for several years, and it has the support of industry and the bureaucracy. But there\u27s no simple or fast way to produce a unique Australian submarine. If the government decides to go down that path, it will have to do so in the knowledge that it\u27s a high stakes venture. This paper describes some of the approaches that could be taken and outlines their pros and cons.
Despite claims to the contrary, there\u27s little doubt that the merger of a European design and American combat system is possibleâafter all, that\u27s what the Collins is. But a sensible early step in the process would be to have government-to-government discussions with the potential playersâespecially in Washingtonâto determine what the actual constraints are, and what\u27s merely unsubstantiated folklore.
Surveying the world market, conventional submarine design capability with the experience and maturity required for our purposes can be found in France, Germany, Japan and Sweden. The UK hasn\u27t designed or built a conventional submarine in over two decades, but the trusted nature of the \u27five eyes\u27 intelligence relationship and its ongoing nuclear submarine programs means that it\u27s also a potential partner
Neutron star binaries and long duration gamma-ray bursts
Cosmological long-duration gamma-ray bursts (LGRBs) are thought to originate
from the core collapse to black holes of stripped massive stars. Those with
sufficient rotation form a centrifugally-supported torus whose collapse powers
the GRB. We investigate the role of tidal locking within a tight binary as a
source of the necessary angular momentum. We find that the binary orbit must be
no wider than a few solar radii for a torus to form upon core collapse.
Comparing this criterion to the observed population of binaries containing two
compact objects suggests that rotation may have been important in the formation
of up to 50% of the observed systems. As these systems created a neutron star
and not a black hole they presumably did not produce highly luminous GRBs. We
suggest instead that they make the subset of GRBs in the relatively local
universe which have much lower luminosity.Comment: 7 pages, accepted for publication in MNRA
Taking wing: time to decide on the F-35 Joint Strike Fighter
Summary: The government is about to make a decision on whether to spend between $8 and 10 billion of taxpayerâs money on the new F-35 Joint Strike Fighter. Itâs also an important call because it will cement the F-35 as the main instrument of Australian air-power for decades into the future.
The F-35 has a troubled pastâmanagement issues and the enormous complexity of the project have caused significant cost and schedule overruns. But now it seems to be on track to come into service with the RAAF in 2020, and to be a very capable aircraft.
The other option is a further purchase of less-advanced Super Hornets, which would come with a marginally lower price tag. But that choice would come at a cost to Canberraâs relationship with Washington as we pulled out of the US-run program, and provide less capability in a region replete with rapid military modernisation
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