An ENO-Based Method for Second-Order Equations and Application to the Control of Dike Levels

This work aims to model the optimal control of dike heights. The control problem leads to so-called Hamilton-Jacobi-Bellman (HJB) variational inequalities, where the dike-increase and reinforcement times act as input quantities to the control problem. The HJB equations are solved numerically with an Essentially Non-Oscillatory (ENO) method. The ENO methodology is originally intended for hyperbolic conservation laws and is extended to deal with diffusion-type problems in this work. The method is applied to the dike optimisation of an island, for both deterministic and stochastic models for the economic growth.     

WENO Scheme with Subcell Resolution for Computing Nonconservative Euler Equations with Applications to One-Dimensional Compressible Two-Medium Flows

High order path-conservative schemes have been developed for solving nonconservative hyperbolic systems in (Parés, SIAM J.?Numer. Anal. 44:300?C321, 2006; Castro et al., Math. Comput. 75:1103?C1134, 2006; J.?Sci. Comput. 39:67?C114, 2009). Recently, it has been observed in (Abgrall and Karni, J.?Comput. Phys. 229:2759?C2763, 2010) that this approach may have some computational issues and shortcomings. In this paper, a modification to the high order path-conservative scheme in (Castro et al., Math. Comput. 75:1103?C1134, 2006) is proposed to improve its computational performance and to overcome some of the shortcomings. This modification is based on the high order finite volume WENO scheme with subcell resolution and it uses an exact Riemann solver to catch the right paths at the discontinuities. An application to one-dimensional compressible two-medium flows of nonconservative or primitive Euler equations is carried out to show the effectiveness of this new approach.     

User-configurable semantic home automation

The ideas of smart home and home automation have been proposed for many years. However, when discussing homes of the future, related studies have usually focused on deploying various smart appliances (or devices) within a home environment and employing those appliances automatically by pre-defined procedures. The difficulties of supporting user-configurable automation are due to the complexity of various dynamic home environments. Moreover, within their home domains, users usually think semantically; for example, “I want to turn off all the lights on the second floor”. This paper proposes a semantic home automation system, USHAS (User-configurable Semantic Home Automation System), which adopts Web Service and WSBPEL for executing automated process; OWL and OWL-S for defining home environments and service ontology; and a self-defined markup language, SHPL (Semantic Home Process Language), for describing semantic processes.     

A family of non-conforming elements and the analysis of Nitsche’s method for a singularly perturbed fourth order problem

In this paper we address several issues arising from a singularly perturbed fourth order problem with small parameter ε. First, we introduce a new family of non-conforming elements. We then prove that the corresponding finite element method is robust with respect to the parameter ε and uniformly convergent to order h ^1/2. In addition, we analyze the effect of treating the Neumann boundary condition weakly by Nitsche’s method. We show that such treatment is superior when the parameter ε is smaller than the mesh size h and obtain sharper error estimates. Such error analysis is not restricted to the proposed elements and can easily be carried out to other elements as long as the Neumann boundary condition is imposed weakly. Finally, we discuss the local error estimates and the pollution effect of the boundary layers in the interior of the domain.     

Nodal DG-FEM solution of high-order Boussinesq-type equations

A discontinuous Galerkin finite-element method (DG-FEM) solution to a set of high-order Boussinesq-type equations for modelling highly nonlinear and dispersive water waves in one horizontal dimension is presented. The continuous equations are discretized using nodal polynomial basis functions of arbitrary order in space on each element of an unstructured computational domain. A fourth-order explicit Runge-Kutta scheme is used to advance the solution in time. Methods for introducing artificial damping to control mild nonlinear instabilities are also discussed. The accuracy and convergence of the model with both h (grid size) and p (order) refinement are confirmed for the linearized equations, and calculations are provided for two nonlinear test cases in one horizontal dimension: harmonic generation over a submerged bar, and reflection of a steep solitary wave from a vertical wall. Test cases for two horizontal dimensions will be considered in future work.     

A study of amorphous and crystalline phases in In2O3-10 wt.% ZnO thin films deposited by DC magnetron sputtering

We report on the processing, phase stability, and electronic transport properties of indium oxide (In₂O₃) doped with 10 wt.% zinc oxide (ZnO) deposited to a thickness of 100 nm using DC magnetron sputter deposition at room temperature and 350 °C. We compare the optimum oxygen content in the sputter gas for pure In₂O₃ and doped with (i) 10 wt.% ZnO and (ii) 9.8 wt.% SnO₂. Amorphous IZO films were annealed at 200 °C in air and N₂/H₂ and resistivity, Hall mobility, and carrier density along with molar volume change were monitored simultaneously as a function of time at temperature. We report that annealing the amorphous oxide in air at 200 °C does not lead to crystallization but does result in a 0.5% decrease in the amorphous phase molar volume and an associated drop in carrier density. Annealing in forming gas leads to an increase in carrier density and a small decrease in molar volume. We also report that when annealed in air at 500 °C, the amorphous IZO phase may crystallize either in the cubic bixbyite or in a recently observed rhombohedral phase.     

A superposition method to calculate the interaction effect between bodies in diffusion theory

We introduce a method for calculating the neutron flux around a finite number of spheres arranged in-line. The method uses the concept of superposition in which the solution for a group of spheres is composed of a sum of solutions for the individual spheres. We illustrate the method by a simple example based on a chain of highly absorbing spheres in a non-absorbing moderator and show that it converges rapidly to the exact solution.     

On bounds for the existence of a bistable controller

By we shall denote the set of polynomials nonzero on the closed disk {z: |z|r}. The problem to be studied is given as follows.Avoidance Problem. Given polynomials A and B, nonnegative integers n, m, and positive numbers r₁, r₂, r₃, determine if there exist , with degrees n and m, respectively, such that AP+BQ is in .It is shown that the Avoidance Problem for r₁=r₂=r₃=1 is equivalent to the well-known Bistable Stabilization Problem for a large class of control systems.Also, a general class of optimization problems for solving the Avoidance Problem is introduced. The class of optimization problems includes problems with sets more general than disks . In addition, an algorithm is proposed for solving these optimization problems, and numerical experience is reported.As an application, bistable controllers for the plant are shown to exist for values of β as low as 0.0246, thus improving on previously reported results by Blondel et al. for this difficult case.Furthermore, it is shown how in some cases it is possible to find optimal controllers by using a combination of numerical and algebraic techniques, and a variant of the algorithm already introduced. As an example, a low order controller is found for for the case when .This method could be applied to other problems where the plant depends on a parameter.     

The constrained longest common subsequence problem

This paper considers a constrained version of longest common subsequence problem for two strings. Given strings S₁, S₂ and P, the constrained longest common subsequence problem for S₁ and S₂ with respect to P is to find a longest common subsequence lcs of S₁ and S₂ such that P is a subsequence of this lcs. An O(rn²m²) time algorithm based upon the dynamic programming technique is proposed for this new problem, where n, m and r are lengths of S₁, S₂ and P, respectively.     

Agents and markets

Autonomous agents are intelligent software programs. Typically, agents are situated in an environment. Repeatedly, they sense their environment, engage in some decision making whereby they select actions, and execute their actions, which, in turn, impact their environment. Moreover, in most cases, the environment contains a number of such agents whose actions typically mutually affect one another. This interdependence arises because the different agents, with their own aims and objectives, must operate in a common environment that has finite resources and capabilities. Depending on the dependency's nature, several different types of social interaction occur between the agents, including cooperation, coordination, and negotiation. Autonomous agents are becoming active participants in marketplaces. We present a study on the interactions between autonomous agents and markets.