Inverse, forward and other dynamic computations computationally optimized with sparse matrix factorizations

We propose an algorithm to compute the dynamics of articulated rigid-bodies with different sensor distributions. Prior to the on-line computations, the proposed algorithm performs an off-line optimisation step to simplify the computational complexity of the underlying solution. This optimisation step consists in formulating the dynamic computations as a system of linear equations. The computational complexity of computing the associated solution is reduced by performing a permuted LU-factorisation with off-line optimised permutations. We apply our algorithm to solve classical dynamic problems: inverse and forward dynamics. The computational complexity of the proposed solution is compared to `gold standard' algorithms: recursive Newton-Euler and articulated body algorithm. It is shown that our algorithm reduces the number of floating point operations with respect to previous approaches. We also evaluate the numerical complexity of our algorithm by performing tests on dynamic computations for which no gold standard is available.Comment: 8 pages, 2 figure, conference RCAR 201

COMMON-PROPERTY RESOURCE USE AND OUTSIDE OPTIONS: COOPERATION ACROSS GENERATIONS IN A DYNAMIC GAME

This paper presents a noncooperative dynamic game with overlapping generations of players using a common-property natural resource, and identifies conditions under which cooperation is supported as an equilibrium of the game. It explores how heterogeneity among the resource users and access to outside markets or microcredit affect local resource use in developing countries.Resource /Energy Economics and Policy,

INTERTEMPORAL PERMIT TRADING FOR STOCK POLLUTANTS WITH UNCERTAINTY

This paper explores the efficiency of tradable permit markets for stock pollutants. With uncertainty about the future stock level or damages, a market with banking and borrowing is inferior, in terms of efficiency, compared to a market without banking and borrowing if the regulator commits to an initial allocation of permits. This result occurs because, with banking and borrowing and commitment, the regulator needs to specify the total allowable amount of emission over time at the initial time period before the uncertainty with the pollution stock is resolved. An alternative banking and borrowing scheme is proposed, where the regulator can update the allocation of permits to firms over time and achieve the efficient pollution accumulation.Environmental Economics and Policy,

Dirac gap-induced graphene quantum dot in an electrostatic potential

A spatially modulated Dirac gap in a graphene sheet leads to charge confinement, thus enabling a graphene quantum dot to be formed without the application of external electric and magnetic fields [Appl. Phys. Lett. \textbf{97}, 243106 (2010)]. This can be achieved provided the Dirac gap has a local minimum in which the states become localised. In this work, the physics of such a gap-induced dot is investigated in the continuum limit by solving the Dirac equation. It is shown that gap-induced confined states couple to the states introduced by an electrostatic quantum well potential. Hence the region in which the resulting hybridized states are localised can be tuned with the potential strength, an effect which involves Klein tunneling. The proposed quantum dot may be used to probe quasi-relativistic effects in graphene, while the induced confined states may be useful for graphene-based nanostructures.Comment: 12 pages, 7 figure