A numerical scheme for fully resolved simulation of fluid-particle systems with freely moving rigid particles is developed. The approach is based on a fictitious domain method wherein the entire fluid-particle domain is assumed to be an incompressible fluid but with variable density. The flow inside the particle domain is constrained to be a rigid body motion using an additional rigidity constr...

A numerical scheme for fully resolved simulation of fluid-particle systems with freely moving rigid particles is developed. The approach is based on a fictitious domain method wherein the entire fluid-particle domain is assumed to be an incompressible fluid but with variable density. The flow inside the particle domain is constrained to be a rigid body motion using an additional rigidity constr...

We discuss the problem of time in spherically symmetric pure Einstein gravity with the cosmological term by using an exact solution to the Wheeler-DeWitt equation. A positive definite inner product is defined, based on the momentum constraint rather than the hamiltonian constraint. A natural notion of time is introduced via the Heisenberg equation. This notion enables one to reproduce the time-...

Beginning from the Legendre transform construction of hyperkähler metrics, we analyze the ALF version of the D n metrics. We determine the constraint equation obtained from extremizing the w coordinate of the generating function F (z, ¯ z, u, ¯ u, w) and study its behavior as we send two of the mass parameters of the D n metric to zero. We find that the constraint equation enforces the limit th...

Beginning with the Legendre transform construction of hyperkähler metrics, we analyze the ALF version of the D n metrics. We determine the constraint equation obtained from extremizing the w coordinate of the generating function F (z, ¯ z, u, ¯ u, w) and study its behavior as we send two of the mass parameters of the D n metric to zero. We find that the constraint equation enforces the limit th...

The instantaneous three-dimensional velocity field of a moving surface can be computed from a sequence of dense range data sets. Here we discuss the computation of the underlying motion constraint equation. This involves the evaluation of derivatives of the depth coordinate with respect to the other world coordinates. As these are not evenly sampled the sampling has to be taken into account exp...

Coarse resolution numerical ocean models must typically include a parameterisation for mesoscale turbulence. A common recipe for such parameterisations is to invoke mixing of some tracer quantity, such as potential vorticity or buoyancy. However, it is well known that eddy fluxes include large rotational components which necessarily do not lead to any mixing; eddy diffusivities diagnosed from u...

Software Product Line (SPL) Engineering is about producing a family of products that share commonalities and variabilities. The variability models are used for variability management in SPLs. Currently, the automated analysis of variability models has become an active research area. In this paper we focus on the automated analysis of Orthogonal Variability Model (OVM), which is a modelling lang...

This paper proposes a methodology to decompose organisation or enterprise complexity so that all requirements for a knowledge management system are considered. The technique builds upon soft system methodologies and ‘hard’ system engineering approaches. It begins with the assumption that objectives or outcomes are achieved in an environment that produces or has constraints. These constraints ei...

This paper introduces a new motion planning algorithm for a biped robot. A geometric constraint equation derived by reshaping the existing ZMP equation enables one to treat the kinematics of the biped robot as a "redundant degrees of freedom" system. Using the ZMP constraint equation, a sequential redundancy resolution algorithm is proposed, which ensures the ZMP trajectory, the planned operati...