Investigation of fluid flow in a troque converter's stator using Computational Fluid Dynamics methods

University of Technology, Sydney. Faculty of Engineering and Information Technology.An automotive torque converter is a widely used hydro-mechanical device for transferring engine power to the transmission in the modern automotive industries. The typical three-dimensional geometrical structures of the stator, pump and turbine made this torque converter very complex. The goal of this study is to gain a sound understanding of the complex three-dimensional fluid flow inside the stator. This study was performed using Computational Fluid Dynamics software. For the sake of gaining a sound understanding, all three elements of the torque converter were included in the simulation. The geometry for the torque converter used was a donation from Dr Mahesh Athavale (Manager, CFDRC). However, the construction of the geometry was thoroughly studied to gain a comprehensive understanding of the construction as well as making the necessary changes. The performance of the torque converter was compared with existing data. This was undertaken for the validation of the work. Then the fluid flow was studied for a changed stator blade number. Thus the variation of performance can easily be noticed with the change in the geometrical structure. The effect of pseudo plastic fluid and dilatant fluid was also studied in order to determine the performance characteristics. All these investigations would lead to a clearer realization of the fluid flow inside the stator and thus help to increase the performance of the torque converter. Out of this research studies on torque converter two publications have been produced. 1. IMECE2011-65078: Effects of Number of Stator Blades on the Performance of a Torque Converter, which was published by the ASME conference 2011, held on November 11-17, 2011, Denver, Colorado, USA. 2. 18th AFMC-2012: Numerical Study of Performance of a Torque Converter Employing a Power-Law Fluid, which was published by the AFMC on its 18th conference, held on December 3-7, 2012, Launceston, Tasmania, Australia

Drug resistance in Plasmodium falciparum from the Chittagong Hill Tracts, Bangladesh.

OBJECTIVE: To assess the efficacy of antimalarial treatment and molecular markers of Plasmodium falciparum resistance in the Chittagong Hill Tracts of Bangladesh. METHODS: A total of 203 patients infected with P. falciparum were treated with quinine 3 days plus sulphadoxine/pyrimethamine (SP) combination therapy, and followed up during a 4-week period. Blood samples collected before treatment were genotyped for parasite mutations related to chloroquine (pfcrt and pfmdr1 genes) or SP resistance (dhfr and dhps). RESULTS: Of 186 patients who completed follow-up, 32 patients (17.2%) failed to clear parasitaemia or became positive again within 28 days after treatment. Recurring parasitaemia was related to age (chi(2) = 4.8, P < 0.05) and parasite rates on admission (t = 3.1, P < 0.01). PCR analysis showed that some of these cases were novel infections. The adjusted recrudescence rate was 12.9% (95% CI 8.1-17.7) overall, and 16.6% (95% CI 3.5-29.7), 15.5% (95% CI 8.3-22.7) and 6.9% (95% CI 0.4-13.4) in three age groups (<5 years, 5-14, > or =15). The majority of infections carried mutations associated with chloroquine resistance: 94% at pfcrt and 70% at pfmdr. Sp-resistant genotypes were also frequent: 99% and 73% of parasites carried two or more mutations at dhfr and dhps, respectively. The frequency of alleles at dhfr, dhps and pfmdr was similar in cases that were successfully treated and those that recrudesced. CONCLUSIONS: The clinical trial showed that quinine 3-days combined to SP is still relatively effective in the Chittagong Hill Tracts. However, if this regimen is continued to be widely used, further development of SP resistance and reduced quinine sensitivity are to be expected. The genotyping results suggest that neither chloroquine nor SP can be considered a reliable treatment for P. falciparum malaria any longer in this area of Bangladesh

Time for pulse traversal through slabs of dispersive and negative (ϵ\epsilon, μ\mu) materials

The traversal times for an electromagnetic pulse traversing a slab of dispersive and dissipative material with negative dielectric permittivity ($\epsilon$) and magnetic permeability ($\mu$) have been calculated by using the average flow of electromagnetic energy in the medium. The effects of bandwidth of the pulse and dissipation in the medium have been investigated. While both large bandwidth and large dissipation have similar effects in smoothening out the resonant features that appear due to Fabry-P\'{e}rot resonances, large dissipation can result in very small or even negative traversal times near the resonant frequencies. We have also investigated the traversal times and Wigner delay times for obliquely incident pulses and evanescent pulses. The coupling to slab plasmon polariton modes in frequency ranges with negative $\epsilon$ or $\mu$ is shown to result in large traversal times at the resonant conditions. We also find that the group velocity mainly contributes to the delay times for pulse propagating across a slab with n=-1. We have checked that the traversal times are positive and subluminal for pulses with sufficiently large bandwidths.Comment: 9 pages, 9 figures, Submitted to Phys. Rev.

Surface plasmon coupled emission enhancement with nanoparticles in the metal layer

We show that it is possible to enhance surface plasmon coupled emission (SPCE) intensity by ∼55% using two dimensional periodic nanoparticle arrays in the glass-metal layer interface of an SPCE structure. The nanoparticles act as coupled nanoantennas. With optimized dimensions and periodicity, the nanoparticle arrays resonate and re-emit intensified SPCE. In this work, two types of nanoparticles such as cuboids and hemispheres are used in the arrays. The optimized dimensions and periodicity of the nanoparticle arrays that lead to enhanced intensity are calculated using the particle swarm algorithm. The increased SPCE intensity will be helpful for using SPCE as a biomolecule detection scheme

An efficient plasmonic photovoltaic structure using silicon strip-loaded geometry

We show that a silicon thin-film photovoltaic structure with silicon strips on the top and grooves on the silver back contact layer can absorb incident solar energy over a broad spectral range. The silicon strips on the top scatter the incident light and significantly help couple to the photonic modes in the smaller wavelength range. The grooves on the silver back contact layer both scatter the incident light and help couple to the photonic modes and resonant surface plasmon polaritons. We find an increase of ∼46% in total integrated solar absorption in the proposed strip-loaded structure compared to that in a planar thin film structure of same dimensions. The proposed structure offers simpler fabrication compared to similar plasmonic-inspired designs

Natural organic matter in sedimentary basins and its relation to arsenic in anoxic ground water: the example of West Bengal and its worldwide implications

In order to investigate the mechanism of As release to anoxic ground water in alluvial aquifers, the authors sampled ground waters from 3 piezometer nests, 79 shallow (80 m) wells, in an area 750 m by 450 m, just north of Barasat, near Kolkata (Calcutta), in southern West Bengal. High concentrations of As (200-1180 mug L-1) are accompanied by high concentrations of Fe (3-13.7 mgL(-1)) and PO4 (1-6.5 mg L-1). Ground water that is rich in Mn (1-5.3 mg L-1) contains <50 mug L-1 of As. The composition of shallow ground water varies at the 100-m scale laterally and the metre-scale vertically, with vertical gradients in As concentration reaching 200 mug L-1 m(-1). The As is supplied by reductive dissolution of FeOOH and release of the sorbed As to solution. The process is driven by natural organic matter in peaty strata both within the aquifer sands and in the overlying confining unit. In well waters, thermotolerant coliforms, a proxy for faecal contamination, are not present in high numbers (<10 cfu/100 ml in 85% of wells) showing that faecally-derived organic matter does not enter the aquifer, does not drive reduction of FeOOH, and so does not release As to ground water.Arsenic concentrations are high (much greater than50 mug L-1) where reduction of FeOOH is complete and its entire load of sorbed As is released to solution, at which point the aquifer sediments become grey in colour as FeOOH vanishes. Where reduction is incomplete, the sediments are brown in colour and resorption of As to residual FeOOH keeps As concentrations below 10 mug L-1 in the presence of dissolved Fe. Sorbed As released by reduction of Mn oxides does not increase As in ground water because the As resorbs to FeOOH. High concentrations of As are common in alluvial aquifers of the Bengal Basin arise because Himalayan erosion supplies immature sediments, with low surface-loadings of FeOOH on mineral grains, to a depositional environment that is rich in organic mater so that complete reduction of FeOOH is common. (C) 2004 Published by Elsevier Ltd

A blind hierarchical coherent search for gravitational-wave signals from coalescing compact binaries in a network of interferometric detectors

We describe a hierarchical data analysis pipeline for coherently searching for gravitational wave (GW) signals from non-spinning compact binary coalescences (CBCs) in the data of multiple earth-based detectors. It assumes no prior information on the sky position of the source or the time of occurrence of its transient signals and, hence, is termed "blind". The pipeline computes the coherent network search statistic that is optimal in stationary, Gaussian noise, and allows for the computation of a suite of alternative statistics and signal-based discriminators that can improve its performance in real data. Unlike the coincident multi-detector search statistics employed so far, the coherent statistics are different in the sense that they check for the consistency of the signal amplitudes and phases in the different detectors with their different orientations and with the signal arrival times in them. The first stage of the hierarchical pipeline constructs coincidences of triggers from the multiple interferometers, by requiring their proximity in time and component masses. The second stage follows up on these coincident triggers by computing the coherent statistics. The performance of the hierarchical coherent pipeline on Gaussian data is shown to be better than the pipeline with just the first (coincidence) stage.Comment: 12 pages, 3 figures, accepted for publication in Classical and Quantum Gravit

A proposal and a theoretical analysis of an enhanced surface plasmon coupled emission structure for single molecule detection

We propose a structure that can be used for enhanced single molecule detection using surface plasmon coupled emission (SPCE). In the proposed structure, instead of a single metal layer on the glass prism of a typical SPCE structure for fluorescence microscopy, a metal-dielectric-metal structure is used. We theoretically show that the proposed structure significantly decreases the excitation volume of the fluorescently labeled sample, and simultaneously increases the peak SPCE intensity and SPCE power. Therefore, the signal-to-noise ratio and sensitivity of an SPCE based fluorescence microscopy system can be significantly increased using the proposed structure, which will be helpful for enhanced single molecule detection, especially, in a less pure biological sample