3,914 research outputs found
Risk assessment in life-cycle costing for road asset management
Queensland Department of Main Roads, Australia, spends approximately A$ 1 billion annually for road infrastructure asset management. To effectively manage road infrastructure, firstly road agencies not only need to optimise the expenditure for data collection, but at the same time, not jeopardise the reliability in using the optimised data to predict maintenance and rehabilitation costs. Secondly, road agencies need to accurately predict the deterioration rates of infrastructures to reflect local conditions so that the budget estimates could be accurately estimated. And finally, the prediction of budgets for maintenance and rehabilitation must provide a certain degree of reliability. This paper presents the results of case studies in using the probability-based method for an integrated approach (i.e. assessing optimal costs of pavement strength data collection; calibrating deterioration prediction models that suit local condition and assessing risk-adjusted budget estimates for road maintenance and rehabilitation for assessing life-cycle budget estimates). The probability concept is opening the path to having the means to predict life-cycle maintenance and rehabilitation budget estimates that have a known probability of success (e.g. produce budget estimates for a project life-cycle cost with 5% probability of exceeding). The paper also presents a conceptual decision-making framework in the form of risk mapping in which the life-cycle budget/cost investment could be considered in conjunction with social, environmental and political issues
Identifying relationship between skid resistance and road crashes using probability-based approach
Road accidents are of great concerns for road and transport departments around world, which cause tremendous loss and dangers for public. Reducing accident rates and crash severity are imperative goals that governments, road and transport authorities, and researchers are aimed to achieve. In Australia, road crash trauma costs the nation A1.7 million. Serious injury cases can cost the taxpayer many times the cost of a fatality. Crashes are in general uncontrolled events and are dependent on a number of interrelated factors such as driver behaviour, traffic conditions, travel speed, road geometry and condition, and vehicle characteristics (e.g. tyre type pressure and condition, and suspension type and condition). Skid resistance is considered one of the most important surface characteristics as it has a direct impact on traffic safety. Attempts have been made worldwide to study the relationship between skid resistance and road crashes. Most of these studies used the statistical regression and correlation methods in analysing the relationships between skid resistance and road crashes. The outcomes from these studies provided mix results and not conclusive. The objective of this paper is to present a probability-based method of an ongoing study in identifying the relationship between skid resistance and road crashes. Historical skid resistance and crash data of a road network located in the tropical east coast of Queensland were analysed using the probability-based method. Analysis methodology and results of the relationships between skid resistance, road characteristics and crashes are presented
Bearing-only formation control with auxiliary distance measurements, leaders, and collision avoidance
We address the controller synthesis problem for distributed formation control. Our solution requires only relative bearing measurements (as opposed to full translations), and is based on the exact gradient of a Lyapunov function with only global minimizers (independently from the formation topology). These properties allow a simple proof of global asymptotic convergence, and extensions for including distance measurements, leaders and collision avoidance. We validate our approach through simulations and comparison with other stateof-the-art algorithms.ARL grant W911NF-08-2-0004, ARO grant W911NF-13-1-0350, ONR grants N00014-07-1-0829, N00014-14-1-0510, N00014-15-1-2115, NSF grant IIS-1426840, CNS-1521617 and United Technologies
A universal correction to higher spin entanglement entropy
We consider conformal field theories in 1+1 dimensions with W-algebra
symmetries, deformed by a chemical potential \mu for the spin-three current. We
show that the order \mu^2 correction to the Re'nyi and entanglement entropies
of a single interval in the deformed theory, on the infinite spatial line and
at finite temperature, is universal. The correction is completely determined by
the operator product expansion of two spin-three currents, and by the
expectation values of the stress tensor, its descendants and its composites,
evaluated on the n-sheeted Riemann surface branched along the interval. This
explains the recently found agreement of the order \mu^2 correction across
distinct free field CFTs and higher spin black hole solutions holographically
dual to CFTs with W-symmetry.Comment: Version accepted for publication as Rapid Communications in Phys.
Rev. D. Included an expanded discussion of the prescription used for contact
terms in relevant integrals; typos correcte
A distributed optimization framework for localization and formation control: applications to vision-based measurements
Multiagent systems have been a major area of research for the last 15 years. This interest has been motivated by tasks that can be executed more rapidly in a collaborative manner or that are nearly impossible to carry out otherwise. To be effective, the agents need to have the notion of a common goal shared by the entire network (for instance, a desired formation) and individual control laws to realize the goal. The common goal is typically centralized, in the sense that it involves the state of all the agents at the same time. On the other hand, it is often desirable to have individual control laws that are distributed, in the sense that the desired action of an agent depends only on the measurements and states available at the node and at a small number of neighbors. This is an attractive quality because it implies an overall system that is modular and intrinsically more robust to communication delays and node failures
Thermal one-point functions: CFT's with fermions, large and large spin
We apply the OPE inversion formula on thermal two-point functions of fermions
to obtain thermal one-point function of fermion bi-linears appearing in the
corresponding OPE. We primarily focus on the OPE channel which contains the
stress tensor of the theory. We apply our formalism to the mean field theory of
fermions and verify that the inversion formula reproduces the spectrum as well
as their corresponding thermal one-point functions. We then examine the large
critical Gross-Neveu model in dimensions with even and at
finite temperature. We show that stress tensor evaluated from the inversion
formula agrees with that evaluated from the partition function at the critical
point. We demonstrate the expectation values of 3 different classes of higher
spin currents are all related to each other by numerical constants, spin and
the thermal mass. We evaluate the ratio of the thermal expectation values of
higher spin currents at the critical point to the Gaussian fixed point or the
Stefan-Boltzmann result, both for the large critical model and the
Gross-Neveu model in odd dimensions. This ratio is always less than one and it
approaches unity on increasing the spin with the dimension held fixed. The
ratio however approaches zero when the dimension is increased with the spin
held fixed.Comment: 46 pages, 8 figures, typos correcte
Thermal one point functions, large and interior geometry of black holes
We study thermal one point functions of massive scalars in black
holes. These are induced by coupling the scalar to either the Weyl tensor
squared or the Gauss-Bonnet term. Grinberg and Maldacena argued that the one
point functions sourced by the Weyl tensor exponentiate in the limit of large
scalar masses and they contain information of the black hole geometry behind
the horizon. We observe that the one point functions behave identically in this
limit for either of the couplings mentioned earlier. We show that in an
appropriate large limit, the one point function for the charged black hole
in can be obtained exactly. These black holes in general contain an
inner horizon. We show that the one point function exponentiates and contains
the information of both the proper time between the outer horizon to the inner
horizon as well as the proper length from the inner horizon to the singularity.
We also show that Gauss-Bonnet coupling induced one point functions in
black holes with hyperbolic horizons behave as anticipated by
Grinberg-Maldacena. Finally, we study the one point functions in the background
of rotating BTZ black holes induced by the cubic coupling of scalars.Comment: 40 pages, 4 figures, 1 table, reference added, typos correcte
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