We consider a twoor three-dimensional time-dependent diffusion-convection-reaction problem and its discretization by the method of characteristics and standard finite elements. We perform the a posteriori error analysis of this discretization and prove optimal error estimates, which lead to an efficient adaptivity strategy both for the time step and the spatial mesh. The estimates are robust wi...

(1.1) ∂tb(x, u) + div(F̄ (t, x, u)− k∇u) = f(t, x, u, s), s(t, x) = ∫ t 0 K(t, z)ψ(u(z, x))dz in Ω × (0, T ], T < ∞, Ω ⊂ R is a bounded domain, ∂Ω ∈ C, see [26]. If Ω is convex, then ∂Ω is assumed to be Lipschitz continuous. We consider a Dirichlet boundary condition (1.2) u(t, x) = 0 on I × ∂Ω, I = (0, T ], together with the initial condition (1.3) u(0, x) = u0(x) x ∈ Ω. We assume 0 < ε ≤ ∂sb(x...

In design of many image processing methods and algorithms, it is assumed that noise is i.i.d. However, noise in real life images is often spatially correlated. Ignoring this fact can lead to certain problems such as reduction of filter efficiency, misdetection of edges, etc. Thus, noise characteristics, namely, variance and spatial spectrum are to be estimated. This should be often done in a bl...

This paper presents the backward method of characteristics for simulating multidimensional transient and steady state radiative heat transfer. This method is based on the method of characteristics that follows photons along their pathlines. It makes use of a fixed grid and unlike the conventional method of characteristics, it follows the photons backward in time. The method (1) is accurate, (2)...

We have transformed the scalar wave equation into a matrix eigenvalue equation, the diagonalization of which gives the guided modes and a discrete representation of the radiation modes. The method is simple and can be used for arbitrary refractive index profdes. I

MgO is an important inorganic material, which can be used in many aspects, such as catalyst, toxic-waste remediation agent, adsorbent, and others. In order to make use of MgO, nano-MgO was prepared by ultrasonic method using Mg (CH3COO)2.2H2O as precursor, NaOH aqueous solution as precipitant in this paper. Effect factors on MgO nano-particle size were investigated. Characteristics of samples w...

PURPOSE Wisdom has received increasing attention in empirical research in recent years, especially in gerontology and psychology, but consistent definitions of wisdom remain elusive. We sought to better characterize this concept via an expert consensus panel using a 2-phase Delphi method. DESIGN AND METHODS A survey questionnaire comprised 53 Likert scale statements related to the concepts of...

Mathematical modeling at the level of the full cardiovascular system requires the numerical approximation of solutions to a one-dimensional nonlinear hyperbolic system describing flow in a single vessel. This model is often simulated by computationally intensive methods like finite elements and discontinuous Galerkin, while some recent applications require more efficient approaches (e.g. for re...

We evaluated the electromagnetic-interference characteristics of MIMO (Multiple Input Multiple Output ) WLAN (Wireless Local Aria Network) by using an opened PW (Parallel Wired) cell that was placed in a radio anechoic chamber. We used two types of the interference wave such as the narrowband AM (Amplitude Modulation) wave specified by the IEC 61000-4-3 standards and the broadband communication...

Expertise of packaging for optoelectronic components requires the solution of optical, mechanical and electrical problems in the same way. The purpose of this study is to present three-dimensional simulations using finite element method (FEM) of thermomechanical stresses and strains in transmitter Laser modules induced by Nd:YAG crystal Laser welds on main sub-assembly Laser submount. Non-linea...