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General method for exponential-type equations for eight- and nine-point prismatic arrays

Description: The results of three-parameter experiments are commonly interpreted by the trilinear equation for eight data in a prismatic array. Ifa center point estimate is available, the eight-and nine-point arrays can be represented by new exponential-type equations. The equations are easy to generate, they are invariant under data translation, and they estimate curvature coefficients.
Date: January 1, 2009
Creator: Silver, Gary L
Partner: UNT Libraries Government Documents Department

Generalized Monge-Kantorovich optimization for grid generation and adaptation in LP

Description: The Monge-Kantorovich grid generation and adaptation scheme of is generalized from a variational principle based on L{sub 2} to a variational principle based on L{sub p}. A generalized Monge-Ampere (MA) equation is derived and its properties are discussed. Results for p > 1 are obtained and compared in terms of the quality of the resulting grid. We conclude that for the grid generation application, the formulation based on L{sub p} for p close to unity leads to serious problems associated with the boundary. Results for 1.5 {approx}< p {approx}< 2.5 are quite good, but there is a fairly narrow range around p = 2 where the results are close to optimal with respect to grid distortion. Furthermore, the Newton-Krylov methods used to solve the generalized MA equation perform best for p = 2.
Date: January 1, 2009
Creator: Delzanno, G L & Finn, J M
Partner: UNT Libraries Government Documents Department

Strong mobility in weakly disordered systems

Description: We study transport of interacting particles in weakly disordered media. Our one-dimensional system includes (i) disorder, the hopping rate governing the movement of a particle between two neighboring lattice sites is inhomogeneous, and (ii) hard core interaction, the maximum occupancy at each site is one particle. We find that over a substantial regime, the root-mean-square displacement of a particle s grows superdiffusively with time t, {sigma}{approx}({epsilon}t){sup 2/3}, where {epsilon} is the disorder strength. Without disorder the particle displacement is subdiffusive, {sigma} {approx}t{sup 1/4}, and therefore disorder strongly enhances particle mobility. We explain this effect using scaling arguments, and verify the theoretical predictions through numerical simulations. Also, the simulations show that regardless of disorder strength, disorder leads to stronger mobility over an intermediate time regime.
Date: January 1, 2009
Creator: Ben-naim, Eli & Krapivsky, Pavel
Partner: UNT Libraries Government Documents Department

Designing a Micro-Mechanical Transistor

Description: This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Micro-mechanical electronic systems are chips with moving parts. They are fabricated with the same techniques that are used to manufacture electronic chips, sharing their low cost. Micro-mechanical chips can also contain electronic components. By combining mechanical parts with electronic parts it becomes possible to process signal mechanically. To achieve designs comparable to those obtained with electronic components it is necessary to have a mechanical device that can change its behavior in response to a small input - a mechanical transistor. The work proposed will develop the design tools for these complex-shaped resonant structures using the geometrical ray technique. To overcome the limitations of geometrical ray chaos, the dynamics of the rays will be studied using the methods developed for the study of nonlinear dynamical systems. T his leads to numerical methods that execute well in parallel computer architectures, using a limited amount of memory and no inter-process communication.
Date: June 3, 1999
Creator: Mainieri, R.
Partner: UNT Libraries Government Documents Department