Studies of microstructural size effect and higher-order deformation in second-order computational homogenization

Two examples illustrating microstructural size effect and higher-order deformation are considered within the context of second-order computational homogenization. Governing equations and appropriate discretization are briefly reviewed, including the scale transition equations and the enforcement of generalised boundary conditions for the RVE (representative volume element). The first example serves as a means of validation for second-order computational homogenization and highlights the difference in terms of higher-order deformation of the RVE between the first and second-order schemes. The second example (indentation test) focuses on microstructural size effect, whereby the result is shown to be dependent on the intrinsic length of the RVE.     

Discrete Particle Swarm Optimization for the minimum labelling Steiner tree problem

Particle Swarm Optimization is a population-based method inspired by the social behaviour of individuals inside swarms in nature. Solutions of the problem are modelled as members of the swarm which fly in the solution space. The improvement of the swarm is obtained from the continuous movement of the particles that constitute the swarm submitted to the effect of inertia and the attraction of the members who lead the swarm. This work focuses on a recent Discrete Particle Swarm Optimization for combinatorial optimization, called Jumping Particle Swarm Optimization. Its effectiveness is illustrated on the minimum labelling Steiner tree problem: given an undirected labelled connected graph, the aim is to find a spanning tree covering a given subset of nodes, whose edges have the smallest number of distinct labels.     

Variable neighbourhood decomposition search for 0–1 mixed integer programs

In this paper we propose a new hybrid heuristic for solving 0–1 mixed integer programs based on the principle of variable neighbourhood decomposition search. It combines variable neighbourhood search with a general-purpose CPLEX MIP solver. We perform systematic hard variable fixing (or diving) following the variable neighbourhood search rules. The variables to be fixed are chosen according to their distance from the corresponding linear relaxation solution values. If there is an improvement, variable neighbourhood descent branching is performed as the local search in the whole solution space. Numerical experiments have proven that exploiting boundary effects in this way considerably improves solution quality. With our approach, we have managed to improve the best known published results for 8 out of 29 instances from a well-known class of very difficult MIP problems. Moreover, computational results show that our method outperforms the CPLEX MIP solver, as well as three other recent most successful MIP solution methods.     

Multiscale modeling of circular and elliptical particles in laminar shear flow

Drug delivery systems for cancer prevention and pain management have been improved related to classical cancer chemotherapy. Nanotechnology with nanoparticles offers new ways in transport of drug molecules and contrast agents by the blood flow through the circulatory system. In this study, we use multiscale mesoscopic bridging procedure of the finite elements (FE) coupled with dissipative particle dynamics (DPD) and lattice Boltzmann (LB) method to model the motion of circular and elliptical particles in a 2-D laminar flow. Four examples are considered: 1) one sedimenting cylinder in a channel, 2) two sedimenting cylinders in a channel, 3) motion of four elliptical particles in a linear shear flow, and 4) motion of circular and elliptical particle in the arterial bifurcation geometry. A good agreement with solution from the literature available was found. These results show that the multiscale approach with coupled FE and DPD/LB methods can effectively be applied to model motion of micro/nanoparticles for a drug delivery system.     

ARTreat Project: three-dimensional numerical simulation of plaque formation and development in the arteries

Atherosclerosis is a progressive disease characterized by the accumulation of lipids and fibrous elements in arteries. It is characterized by dysfunction of endothelium and vasculitis, and accumulation of lipid, cholesterol, and cell elements inside blood vessel wall. In this study, a continuum-based approach for plaque formation and development in 3-D is presented. The blood flow is simulated by the 3-D Navier-Stokes equations, together with the continuity equation while low-density lipoprotein (LDL) transport in lumen of the vessel is coupled with Kedem-Katchalsky equations. The inflammatory process was solved using three additional reaction-diffusion partial differential equations. Transport of labeled LDL was fitted with our experiment on the rabbit animal model. Matching with histological data for LDL localization was achieved. Also, 3-D model of the straight artery with initial mild constriction of 30% plaque for formation and development is presented.     

A 2×2 Matrix Algebra for Electromagnetic Wave Propagation in Stratified Biaxial Media

We present a new 2×2 matrix algebra for electromagnetic wave propagation in stratified biaxial media. Our method is based on Maxwell's equations and the continuity of the tangential components of the electric and magnetic field vectors and gives an exact complete solution. No restrictions are necessary for the orientations of the axes of the dielectric tensors of the stratified medium and the properties of the incident plane wave. A complete and systematic methodology is provided for calculating all wave parameters and all properties of the reflected and transmitted waves in terms of 2×2 Fresnel reflection and transmission matrices.     

Molecular imprinting of fructose using a polymerizable benzoboroxole: Effective complexation at pH 7.4

Covalent molecularly imprinted polymers against d-fructose employing 5-methacrylamido-2-hydroxymethylphenylboronic acid as functional monomer and trimethylpropane trimethacrylate (TRIM) as the crosslinking agent were prepared by a conventional radical bulk polymerization (MIP-BX(Fru)). Batch binding studies for fructose in aqueous buffers containing 10% methanol revealed that the binding capability of MIP-BX(Fru) is paramount compared to a MIP prepared with vinylphenylboronic acid MIP-BA(Fru). Especially, at the biological important pH-value of 7.4 the rebinding of fructose to the MIP-BX(Fru) is with 60 nmol per mg polymer about 3.2 higher compared to the MIP-BA(Fru). A pinacol imprinted polymer was also investigated and showed in case of MIP-BX still an imprinting of 1.7 at pH 7.4 whereas MIP-BA did not show a difference. Cross-reactivity studies at pH 7.4 show the shape-selectivity of the MIP-BX(Fru) in the order of l-fructose, sorbitol, glucose and sucrose.     

An improvement of AODV protocol for the overhead reduction in scalable dynamic wireless ad hoc networks

Wireless Networks - In this paper, the problem of improving reliability and reducing routing overhead in dynamic scalable Wireless Ad hoc NETworks (WANETs) is considered. Having in mind that the...     

A FEM-based direct method for material reconstruction inverse problem in soft tissue elastography

A novel finite element method (FEM) based direct method is developed for the material reconstruction inverse problem in soft tissue elastography. The solution is obtained by minimising an objective function, defined as the sum of the square of the residual norms at all nodes, where the nodal residual norm is defined as a linear function of elasticity parameters of the associated elements. The measured deformation is enforced directly and satisfying the equilibrium at every node is utilised as the optimisation objective. As a result, the soft tissue elastography can be obtained directly by solving the resulting set of linear equations.     

Rejection of PSK interference in DS-SS/QPSK system using complexadaptive filter and nonlinear correlation receiver

The authors investigate the rejection of PSK interference in a DS-SS/QPSK system using a complex adaptive filter and a nonlinear correlation receiver with soft-limiter. This system leads to a decrease in error probability for several orders of magnitude compared to the system which uses a complex adaptive filter and a linear receiver