Statistical experimental design to optimize formulations for foam vinyl applications

Statistical experimental design has been used to study the effects of blowing agents, processing aids and fillers in rigid vinyl foam formulations. It is shown how this approach provides information about interactions between variables and can be used to help to predict an optimum formulation.     

Experimental and theoretical studies on the corrosion inhibition of vitamins – Thiamine hydrochloride or biotin in corrosion of mild steel in aqueous chloride environment

The corrosion inhibition of thiamine hydrochloride (vitamin B1) or biotin (vitamin B7) on corrosion of mild steel in 240 ppm chloride ions solution was studied using weight loss method, potentiodynamic polarization curves and electrochemical impedance spectroscopy. UV–Vis, FTIR and surface analysis using SEM and EDS characterization were carried out to understand the corrosion inhibition property of these inhibitors in 240 ppm aqueous chloride medium. Experimental results show that both thiamine hydrochloride and biotin act as a good corrosion inhibitors. Quantum chemical parameters obtained from density functional theory (DFT) calculations were discussed with experimental results.     

Online complete coverage path planning using two-way proximity search

This paper presents an efficient online approach for complete coverage path planning of mobile robots in an unknown workspace based on online boustrophedon motion and an optimized backtracking mechanism. The presented approach first performs a single continuous boustrophedon motion until a critical point is reached. In order to completely cover the environment, next starting point is decided by using the accumulated knowledge of the environment map. An efficient backtracking technique based on proposed Two-way Proximity Search algorithm is used to plan a path from the critical point to the new starting point. Simulation results show the efficiency of proposed backtracking approach with improved total coverage time, coverage path length and memory requirements.     

Influence of heat transfer on a peristaltic flow of Johnson Segalman fluid in a non uniform tube

The present investigation deals with the peristaltic motion of an incompressible non-Newtonian fluid in a non-uniform tube for long wavelength. The mechanical properties of the material are represented by the constitutive equation for a Johnson Segalman fluid. The resulting problem for velocity field and temperature profile is solved using (i) Regular perturbation method (ii) Homotopy analysis method. The influence of various emerging parameters on the flow is shown through graphs and discussed.     

Peristaltic flow of a Williamson fluid in an inclined asymmetric channel with partial slip and heat transfer

The present article deals with the peristaltic flow of a Williamson fluid in an inclined asymmetric channel. The relevant equations have been modeled. Analysis has been carried out in the presence of velocity and thermal slip conditions. Expressions for stream function, temperature, pressure gradient and heat transfer coefficients are derived. The solutions are compared with the existing available results in a limiting sense. Numerical integration has been performed for pressure rise per wavelength. Plots are presented and analyzed for various embedded parameters into the problem. Comparison between the solutions is also shown.     

Peristaltic flow of a Phan‐Thien‐Tanner nanofluid in a diverging tube

The present study examines the peristaltic flow of a PTT nanofluid in a diverging tube. This is the first article on the PTT peristaltic flow in nanofluid. The governing equations for PTT nanofluid are modelled in a cylindrical coordinates system. The flow is investigated in a wave frame of reference moving with velocity of the wave c₁. Temperature and nanoparticle equations are coupled so the homotopy perturbation method is used to calculate the solutions of temperature and nanoparticle equations, while exact solutions have been evaluated for the velocity profile and pressure gradient. The solutions analyze the Brownian motion number N_b, thermophoresis number N_t, local temperature Grashof number B_r, and local nanoparticle Grashof number G_r. The effects of various physical parameters of the model are investigated and discussed. It is observed that the pressure rise decreases with the increase in thermophoresis number N_t. Increases are noted in the Brownian motion parameter N_b and the thermophoresis parameter N_t as the temperature profile increases. Streamlines have been plotted at the end of the article. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20386     

Fabrication and evaluation studies of novel polyvinylpyrrolidone and 2-acrylamido-2-methylpropane sulphonic acid-based crosslinked matrices for controlled release of acyclovir

Polymer Bulletin - The aim of the present study was to fabricate chemically crosslinked matrix system of polyvinylpyrrolidone (PVP)-co-poly 2-acrylamido-2-methylpropane sulphonic acid (AMPS)...     

Blood lead concentrations and iron deficiency in Canadian aboriginal infants

Aboriginal Cree infants living in northern Quebec who were 9 months of age were screened for anemia, iron deficiency and elevated blood lead concentrations. Of the 314 infants who were eligible to participate, 274 (87.3%) were screened for anemia, 186 had blood lead concentration measured and 141 of the latter group had iron status determined. The median blood lead concentration was 0.08 micromol/l (range 0.01-1.00 micromol/l). The 25, 50 and 75 percentiles for blood lead concentration were 0.05, 0.08 and 0.12 micromol/l, respectively. The prevalence of elevated blood lead concentrations (> 0.48 micromol/l) was 2.7% (95% Cl 0.36-5.0). Among infants who had blood lead measured, the prevalence of anemia (hemoglobin < 110 g/l) was 25.0% and 7.9% of infants had iron-deficiency anemia (hemoglobin < 110 g/l and serum ferritin < 10 microg/l). Anemic infants had a higher mean geometric blood lead concentration than did babies without anemia (0.11 micromol/l vs. 0.07 micromol/l, P = 0.003). Likewise, infants with iron-deficiency anemia had a significantly higher mean geometric blood lead concentration than infants without iron deficiency anemia (0.16 micromol/l vs. 0.07 micromol/l, P = 0.001). There was a significant negative correlation between blood lead and hemoglobin concentrations (r = -0.203, P = 0.006) and between blood lead and serum ferritin concentrations (r = -0.245, P = 0.003). Infants who were fed traditional food (fish, fowl and game) did not have a significantly different mean geometric blood lead concentration, hemoglobin concentration or serum ferritin concentration than infants who did not eat traditional food. Few infants (5.3%) ate traditional food daily.     

Implementation of mixed time integration techniques on a vectorized computer with shared memory

The implementation of subcycling in an explicit finite element program executed on a concurrent computer with shared memory is described. The effects of vectorization and parallelization on the speed-up and efficiency achieved with subcycling is discussed. Numerical studies are presented to illustrate the effects of the number of processors, the size of element blocks and problem size. Finally, an efficient allocation algorithm which minimizes the effects of processor idleness is presented.