Stair-climbing wheelchair.q05: from the concept to the prototype

In this paper, an electric stair-climbing wheelchair, named wheelchair.q05, able to move on flat ground and to climb stairs, is presented. The proposed solution has been developed through a series of studies and designs, all based on a smart hybrid triple leg-wheel locomotion unit. The stability of the device is guaranteed by a rear support of a pair of pivoting wheels during motion on flat ground, and by the support of an idle track, when climbing on or going down stairs. By means of mechanisms and actuators, it is possible to change the configuration of the wheelchair, from the flat ground motion to the stair climbing configuration

The pairing Hamiltonian for one pair of identical nucleons bound in a potential well

The problem of one pair of identical nucleons sitting in ${\cal N}$ single particle levels of a potential well and interacting through the pairing force is treated introducing even Grassmann variables. The eigenvectors are analytically expressed solely in terms of these with coefficients fixed by the eigenvalues and the single particle energies. When the latter are those of an harmonic oscillator well an accurate expression is derived for both the collective eigenvalue and for those trapped in between the single particle levels, for any strength of the pairing interaction and for any number of levels. Notably the trapped solutions are labelled through an index upon which they depend parabolically.Comment: 5 pages, 1 postscript figur

Agent-based simulation of a project fractal company

In response to competitive pressures small and medium enterprises have begun to form alliances between them. This allows each company to increase their ability to react and adapt to changes in their business environment, concentrating on their core competencies, increase the availability of resources and gain economies of scale. Thus, the project-based fractal company model enables virtual and temporary integration between different companies to achieve specific business objectives. The successful implementation of the model lies in the establishment of client-server relationships between project managers. This paper analyses the use of agentbased simulation to show behaviors that emerge from the interaction of project managers and resources managers when they establish client-server relationships. To do this, use Netlogo language as a tool intends to demonstrate emergent behavior resulting from interactions between agents of the fractal company.XVII Workshop Agentes y Sistemas Inteligentes (WASI).Red de Universidades con Carreras en Informática (RedUNCI

Agent-based simulation of a project fractal company

In response to competitive pressures small and medium enterprises have begun to form alliances between them. This allows each company to increase their ability to react and adapt to changes in their business environment, concentrating on their core competencies, increase the availability of resources and gain economies of scale. Thus, the project-based fractal company model enables virtual and temporary integration between different companies to achieve specific business objectives. The successful implementation of the model lies in the establishment of client-server relationships between project managers. This paper analyses the use of agentbased simulation to show behaviors that emerge from the interaction of project managers and resources managers when they establish client-server relationships. To do this, use Netlogo language as a tool intends to demonstrate emergent behavior resulting from interactions between agents of the fractal company.XVII Workshop Agentes y Sistemas Inteligentes (WASI).Red de Universidades con Carreras en Informática (RedUNCI

The many levels pairing Hamiltonian for two pairs

We address the problem of two pairs of fermions living on an arbitrary number of single particle levels of a potential well (mean field) and interacting through a pairing force. The associated solutions of the Richardson's equations are classified in terms of a number $v_l$, which reduces to the seniority $v$ in the limit of large values of the pairing strength $G$ and yields the number of pairs not developing a collective behaviour, their energy remaining finite in the $G\to\infty$ limit. We express analytically, through the moments of the single particle levels distribution, the collective mode energy and the two critical values $G_{\rm cr}^{+}$ and $G_{\rm cr}^{-}$ of the coupling which can exist on a single particle level with no pair degeneracy. Notably $G_{\rm cr}^{+}$ and $G_{\rm cr}^{-}$ merge when the number of single particle levels goes to infinity, where they coincide with the $G_{\rm cr}$ (when it exists) of a one pair system, not envisioned by the Richardson theory. In correspondence of $G_{\rm cr}$ the system undergoes a transition from a mean field to a pairing dominated regime. We finally explore the behaviour of the excitation energies, wave functions and pair transfer amplitudes finding out that the former, for $G>G_{\rm cr}^{-}$, come close to the BCS predictions, whereas the latter display a divergence at $G_{\rm cr}$, signaling the onset of a long range off-diagonal order in the system.Comment: 35 pages, 6 figures, 2 tables, to be published in EPJ