Recent Trends in Computation of Turbulent Jet Impingement Heat Transfer

A review of the current status of computation of turbulent impinging jet heat transfer is presented. It starts with a brief introduction to flow and heat transfer characteristics of jet impinging flows considering the simplest jet impinging geometry: normal impingement of a single jet into a flat surface. Subsequently, a review of recent computational studies related to the same geometry is presented. The effects of different subgrid scale models, boundary conditions, numerical schemes, grid distribution, and size of the computational domain adopted in various large eddy simulations of this flow configuration are reviewed in detail. A review of direct numerical simulation of the same geometry is also presented. Further, some recent attempts in Reynolds-averaged Navier–Stokes modeling of impinging flows are also reviewed. A review of computation of other complex impinging flows is also presented. The review concludes with a listing of some important findings and future directions in the computation of impinging flows.     

A MULTIGRID-ACCELERATED THREE-DIMENSIONAL TRANSIENT-FLOW CODE AND ITS APPLICATION TO A NEW TEST PROBLEM

A multigrid-assisted solver for the three-dimensional time-dependent incompressible Navier-Stokes equations on graded Cartesian meshes is developed. The spatial accuracy is third-order for the convective terms and fourth-order for the viscous terms, and a fractional-step strategy ensures second-order time accuracy. To achieve good time-wise efficiency a multigrid technique is used to solve the highly time-consuming pressure-Poisson equation that requires to be solved at every time step. The speed-up achieved by multigrid is shown in tabular form. The performance and accuracy of the code are first ascertained by computing the flow in a single-sided lid-driven cubic cavity with good grid-economy and comparing the results available in the literature. The code, thus validated, is then applied to a new test problem we propose and various transient and asymptotically obtained steady-state results are presented. Given the care taken to establish the credibility of the code and the good spatio-temporal accuracy of the discretization, these results are accurate and may be used for ascertaining the performance of any computational algorithm applied to this test problem.     

An efficient FE model and Least Square Error method for accurate calculation of transverse shear stresses in composites and sandwich laminates

Accurate evaluation of transverse stresses in laminated composites and sandwich plates using 2D FE models involves cumbersome post-processing techniques. In this paper a simple and efficient method has been proposed for accurate evaluation of through-the-thickness distribution of transverse stresses in composites and sandwich laminates by using a displacement based C⁰ FE model (2D) derived from Refined Higher Order Shear Deformation Theory (RHSDT) and a Least Square Error (LSE) method. The C⁰ FE model satisfies the inter-laminar shear stress continuity conditions at the layer interfaces and zero transverse shear stress conditions at the top and bottom of the plate. In this model the first derivatives of transverse displacement have been treated as independent variables to circumvent the problem of C¹ continuity associated with the above plate theory (RHSDT). The LSE method is applied to the 3D equilibrium equations of the plate problem at the post-processing stage, after in-plane stresses are calculated by using the above FE model based on RHSDT. Thus the proposed method is quite simple and elegant compared to the usual method of integrating the 3D equilibrium equations at the post-processing stage for calculation of transverse stresses in a composite laminate. In the proposed method, the first two equations of equilibrium are utilized to compute the transverse shear stress variation through the thickness of a laminated plate whereas the third equation of equilibrium gives the normal stress variation. Accuracy of the proposed method is demonstrated in the numerical examples through comparison of the present results with those obtained from different models based on higher order shear deformation theory (HSDT) and 3D elasticity solutions.     

Genotype and growing environment influence chickpea (Cicer arietinum L.) seed composition

BACKGROUND: As a first step towards genetic improvement of seed quality in chickpea (Cicer arietinum L.), seven desi and nine kabuli varieties were grown at multiple sites to assess the affect of environment on seed yield, weight and selected seed constituents. The sites were chosen to represent a range of environments in chickpea production areas of the Canadian prairies. RESULTS: Genotype × environment interaction effects on starch, amylose and protein (desi only) concentrations and seed yield were significant, suggesting that the varieties did not perform consistently relative to each other in the different environments. Starch concentration was negatively correlated (r_kabuli = ?0.25, P < 0.05; r_desi = ?0.16, P < 0.05) with protein concentration in both chickpea market classes. However, repeatability estimates of starch, amylose and protein concentrations were low and inconsistent across chickpea market classes, possibly owing to complex biosynthetic pathways for these constituents. CONCLUSION: The results suggest that testing for seed constituent traits over a range of environments will be required to improve seed quality in individual chickpea varieties. The best selection strategies for seed constituent improvement in chickpea will be influenced by genotype and genotype × environment interaction for these traits. The negative relationship between seed constituents and yield indicates that selection for chickpea cultivars with desired seed composition may require compromise and indirect selection. Copyright © 2009 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.     

Role of graphene-based materials (GO) in improving physicochemical properties of cementitious nano-composites: a review

Journal of Materials Science - This work deals with the review of graphene-based cementitious composites, which is primarily focused on the effect on microstructure, hydration mechanism, and...     

A novel automated magnetic resonance image segmentation approach based on elliptical gamma mixture model for breast lumps detection

This article introduces a novel semisupervised automated segmentation approach for breast magnetic resonance (MR) image on multicore CPU-GPU systems. The basic idea of the proposed method is clustering-based semisupervised classifier devised by elliptical gamma mixture model (EGMM). Parameters of EGMM are identified by the iterative log-expectation maximization (EM) algorithm. The suggested classifier labels the groups of voxels in an input image first and then classifies the image slices using the EGMM. Two different implementations of the proposed algorithm have been developed based on two different types of high-performance computing architectures such as graphics processing units (GPUs) and multicore processors. To realize the real-time segmentation performance of our algorithm with two distinctive architecture, we have tested a set of breast MR images collected from MedPix. Comparison between two architectures in terms of segmentation performance and computational cost is assessed by the analysis of simulation and experimental results.     

Bio‐fabrication of silver nanoparticles by Pseudomonas aeruginosa : optimisation and antibacterial activity against selected waterborne human pathogens

Multiple drug resistance and treatment of contaminated water has become a serious issue in past years. Silver nanoparticles (AgNPs), being bactericidal, non‐toxic, cheap and environment friendly behaviour, have drawn attention to overcome these problems. This study has been designed to synthesise AgNPs from Pseudomonas aeruginosa. AgNPs formation was confirmed by colour change and UV–vis spectroscopy. Furthermore, Fourier transform infrared spectroscopy peaks demonstrated the presence of capped proteins as reducing and stabilising agent. Transmission electron microscopy micrograph revealed spherical shape AgNPs with the size ranging between 10 and 20 nm. Antibacterial activity of AgNPs was evaluated against the most prevalent waterborne pathogens enterohaemorrhagic Escherichia coli and Salmonellae typhimurium. Moreover, the antibacterial activity of AgNPs was tested for the treatment of contaminated water which showed attenuation in bacterial load within 8 h as demonstrated by growth kinetics data. Furthermore, AgNPs did not exhibit haemolytic effects on human red blood cells (RBCs) even at 100 mg L⁻¹ concentration of AgNPs. The results herein suggest that AgNPs synthesised by P. aeruginosa under optimised conditions exhibit microbicidal property against waterborne pathogens and having no toxic effect on human RBCs. These AgNPs could be employed for treatment of contaminated water after process optimisation.Inspec keywords: silver, nanoparticles, nanobiotechnology, nanofabrication, microorganisms, antibacterial activity, water treatment, ultraviolet spectra, visible spectra, Fourier transform infrared spectra, transmission electron microscopy, blood, cellular biophysicsOther keywords: biofabrication, silver nanoparticles, Pseudomonas aeruginosa, optimisation, antibacterial activity, waterborne human pathogens, multiple drug resistance, contaminated water treatment, colour change, UV‐vis spectroscopy, Fourier transform infrared spectroscopy, capped proteins, reducing agent, stabilising agent, transmission electron microscopy micrograph, enterohaemorrhagic Escherichia coli, Salmonellae typhimurium, growth kinetics, human red blood cells, microbicidal property, process optimisation, Ag     

Enabling the interactive display of large medical volume datasets by multiresolution bricking

In this paper, we present an approach to interactive out-of-core volume data exploration that has been developed to augment the existing capabilities of the LhpBuilder software, a core component of the European project LHDL (). The requirements relate to importing, accessing, visualizing and extracting a part of a very large volume dataset by interactive visual exploration. Such datasets contain billions of voxels and, therefore, several gigabytes are required just to store them, which quickly surpass the virtual address limit of current 32-bit PC platforms. We have implemented a hierarchical, bricked, partition-based, out-of-core strategy to balance the usage of main and external memories. A new indexing scheme is introduced, which permits the use of a multiresolution bricked volume layout with minimum overhead and also supports fast data compression. Using the hierarchy constructed in a pre-processing step, we generate a coarse approximation that provides a preview using direct volume visualization for large-scale datasets. A user can interactively explore the dataset by specifying a region of interest (ROI), which further generates a much more accurate data representation inside the ROI. If even more precise accuracy is needed inside the ROI, nested ROIs are used. The software has been constructed using the Multimod Application Framework, a VTK-based system; however, the approach can be adopted for the other systems in a straightforward way. Experimental results show that the user can interactively explore large volume datasets such as the Visible Human Male/Female (with file sizes of 3.15/12.03 GB, respectively) on a commodity graphics platform, with ease.     

Approximation Algorithms for the Unsplittable Flow Problem

We present approximation algorithms for the unsplittable flow problem (UFP) in undirected graphs. As is standard in this line of research, we assume that the maximum demand is at most the minimum capacity. We focus on the non-uniform capacity case in which the edge capacities can vary arbitrarily over the graph. Our results are: We obtain an approximation ratio for UFP, where n is the number of vertices, is the maximum degree, and is the expansion of the graph. Furthermore, if we specialize to the case where all edges have the same capacity, our algorithm gives an approximation. For certain strong constant-degree expanders considered by we obtain an approximation for the uniform capacity case. For UFP on the line and the ring, we give the first constant-factor approximation algorithms. All of the above results improve if the maximum demand is bounded away from the minimum capacity. The above results either improve upon or are incomparable with previously known results for these problems. The main technique used for these results is randomized rounding followed by greedy alteration, and is inspired by the use of this idea in recent work.