9,169 research outputs found
Dimensional crossover of the fundamental-measure functional for parallel hard cubes
We present a regularization of the recently proposed fundamental-measure
functional for a mixture of parallel hard cubes. The regularized functional is
shown to have right dimensional crossovers to any smaller dimension, thus
allowing to use it to study highly inhomogeneous phases (such as the solid
phase). Furthermore, it is shown how the functional of the slightly more
general model of parallel hard parallelepipeds can be obtained using the
zero-dimensional functional as a generating functional. The multicomponent
version of the latter system is also given, and it is suggested how to
reformulate it as a restricted-orientation model for liquid crystals. Finally,
the method is further extended to build a functional for a mixture of parallel
hard cylinders.Comment: 4 pages, no figures, uses revtex style files and multicol.sty, for a
PostScript version see http://dulcinea.uc3m.es/users/cuesta/cross.p
Orbital order, stacking defects and spin-fluctuations in the -electron molecular solid RbO
We examine magnon and orbiton behavior in localized O anti-bonding
molecular orbitals using an effective Kugel-Khomskii Hamiltonian
derived from a two band Hubbard model with hopping parameters taken from {\em
ab initio} density functional calculations. The considerable difference between
intraband and interband hoppings leads to a strong coupling between the spin
wave dispersion and the orbital ground state, providing a straightforward way
of experimentally determining the orbital ground state from the measured magnon
dispersion. The near degeneracy of different orbital ordered states leads to
stacking defects which further modulate spin-fluctuation spectra. Proliferation
of orbital domains disrupts long-range magnetic order, thus causing a
significant reduction in the observed N\'eel temperature.Comment: 5 pages, 2 figure
Contingent Claims Valuation of Corporate Liabilities: Theory and Empirical Tests
Although the Contingent Claims Analysis model has become the premier theory of how value is allocated among claimants on firms,its empirical validity remains an open question. In addition to being of academic interest, a test of the model would have significant practical implications. If it can be established that the model predicts actual market prices, then the model can be used to price new and untraded claims, to infer firm values from prices of traded claims like equity and to price covenants separately. In this paper evidence is presented on how well a model which makes the usual assumptions in the literature does in predicting market prices for claims in standard capital structures. The results suggest that the usual assumption list requires modification before it can serve as a basis for valuing corporate claims.
Decentralized formation control with connectivity maintenance and collision avoidance under limited and intermittent sensing
A decentralized switched controller is developed for dynamic agents to
perform global formation configuration convergence while maintaining network
connectivity and avoiding collision within agents and between stationary
obstacles, using only local feedback under limited and intermittent sensing.
Due to the intermittent sensing, constant position feedback may not be
available for agents all the time. Intermittent sensing can also lead to a
disconnected network or collisions between agents. Using a navigation function
framework, a decentralized switched controller is developed to navigate the
agents to the desired positions while ensuring network maintenance and
collision avoidance.Comment: 8 pages, 2 figures, submitted to ACC 201
- …