When a Hamiltonian system has a \Kinetic + Potential" structure, the resulting ow is locally a geodesic ow. But there may be singularities of the geodesic structure, so the local structure does not always imply that the ow is globally a geodesic ow. In order for a ow to be a geodesic ow, the underlying manifold must have the structure of a unit tangent bundle. We develop homological conditions ...

Estimation of growth curves or item response curves often involves monotone data smoothing. Methods that have been studied in the literature tend to be either less exible or more diicult to compute when constraints such as monotonicity are incorporated. Built upon the ideas of Ramsay (1988) and Koenker, Ng and Portnoy (1994), we propose monotone B-spline smoothing based on L 1 optimization. It ...

This paper presents an approach to measuring uid ow from image sequences. The approach centers around a motion recovery algorithm that is based on principles from uid mechanics: The algorithm is constrained so that recovered ows observe conservation of mass as well as physically motivated boundary conditions. Results are presented from application of the algorithm to transmittance imagery of ui...

This paper proposes the use of absorbing Markov chains to solve the capacity constrained transit network loading problem taking common lines into account. The approach handles congested transit networks, where some passengers will not be able to board because of the absence of sufficient space. The model also handles the common lines problem, where choice of route depends on frequency of arriva...

We show short time existence and uniqueness of C solutions to the mean curvature ow with obstacles, when the obstacles are of class C. If the initial interface is a periodic graph we show long time existence of the evolution and convergence to a minimal constrained hypersurface.

We study a simple, kinematical model of a galactic fountain ow and show that a horizontal eld in the galactic plane can be pumped into the halo to a height of several kiloparsecs. This pumping eeect results from the topological structure of the ow in which the updraughts (represented by hot gas) form a connected network, whereas the downdraughts (associated with isolated cool clouds) are discon...

We describe an algorithm that generates prime implicates of equational clause sets without variables and function symbols. The procedure is based on constrained superposition rules, where constraints are used to store literals that are asserted as additional axioms (or hypotheses) during the proof search. This approach is sound and deductive-complete, and it is more e cient than previous algori...

By means of He's homotopy perturbation method (HPM) an approximate solution of velocity eld is derived for the ow in straight pipes of non-Newtonian uid obeying the Sisko model. The nonlinear equations governing the ow in pipe are for- mulated and analyzed, using homotopy perturbation method due to He. Furthermore, the obtained solutions for velocity eld is graphically sketched...

Many code generator generators use tree pattern matching and dynamic programming. This note describes a simple program that generates matchers that are fast, compact, and easy to understand. It is simpler than common alternatives: 200{700 lines of Icon versus 3000 lines of C for Twig and 5000 for burg. Its matchers run up to 25 times faster than Twig's. They are necessarily slower than burg's B...