Numerical investigation of aspect ratio effect on thermal parameters in laminar nanofluid flow in microchannel heat sink

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.In this paper, laminar nanofluid flow of ethylene glycol-based of 4% volume fraction CuO(II) in a silicon rectangular microchannel heat sink with constant hydraulic diameter and different aspect ratios, with a constant heat flux, has been treated numerically. The effect of changing aspect ratios on the pressure loss and thermal parameters of the microchannel, such as Nusselt number(Nu), heat transfer coefficient(h) and non-dimensional temperature in fluid phase and solid(wall) phase have been investigated, using the finite volume method. In addition, the maximum and minimum values of thermal parameters and pressure loss have been calculated and the optimum aspect ratio for the performance of such systems has been evaluated

Effect of nanomaterial properties on thermal conductivity of heat transfer fluids and nanomaterial suspension

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Energy has been rated as the single most important issue facing humanity in the current as well as next 50 years. Securing clean energy has become the top priority of most developed countries. Considering the rapid increase in energy demand worldwide, intensifying the heat transfer process and reducing energy loss due to ineffective use have become an increasingly important task. Fundamentally, energy conversion and transportation occur at atomic or molecular levels, Nanoscience and nanotechnology are expected to play a significant role in revitalizing the traditional energy industries and stimulating the emerging renewable energy industries. Nanofluid is a modern engineering heat transfer fluid with superior potential for enhancing the heat transfer performance of conventional fluids such as water, ethylene glycol and oils. It is consisting of solid nanoparticles with sizes typically of 1–100 nm suspended in base fluids. Many attempts have been made to investigate its important thermal properties, i.e. thermal conductivity; however, no definitive agreements and idea have emerged about this property. This article reports the effect of different nanomaterial on the thermal conductivity enhancement of nanofluids experimentally. TiO2, Fe3O4 and Al2O3 nanoparticles dispersed in water and ethylene glycol with volume concentration of 1 – 7.5 vol. % is used in the present study. A transient hot-wire apparatus (KD2 pro) is used for measuring the thermal conductivity of nanofluids. The results show that all the heat transfer fluids show an increase in thermal conductivity with the addition of nanoparticles in it. The measured thermal conductivity of nanofluids increased as the particle concentrations increased and are higher than the values of the base liquids. This confirms the effect of volume concentration of nanoparticles on the thermal conductivity enhancement

Rapid biosynthesis of silver nanoparticles using bottle gourd fruit extract and potential application as bactericide

Synthesis of silver nanoparticles by biological route represents as economic alternative for physical and chemical methods of nanoparticles formation. Biosynthesis of silver nanoparticles using bottle gourd (Cucurbita lagenaria L.) fruit extract was investigated. Silver nanoparticles were characterized using UV-Vis absorption spectroscopy, absorption peak was obtained at 435 nm. X-Ray diffraction and Scanning Electron Microscopy analysis showed that silver nanoparticles were spherical with average particles size of 27.4 nm. These were found to be toxic against Klebsiella pneumoniae NCIM 2719 and Clostridium acetobutilicum bacteria

Bore well recharging technique

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Predictors of Resilience Among Infants at Risk for Rapid Weight Gain

Objective: The study objective was to investigate factors associated with resilience to rapid weight gain (RWG) among predominantly bottle-fed infants. Methods: Data came from 1,353 mothers who participated in the Infant Feeding Practices Study 2. Mothers completed a prenatal questionnaire and monthly surveys of infant feeding and growth between birth and 12 months. Infants were classified as resilient if they were predominantly bottle fed but did not exhibit RWG between birth and the latter half of infancy (≥ +0.67 change in weight-for-age z score). Results: Thirty-five percent of the sample (n = 467) was predominantly bottle fed but did not exhibit RWG (“Resilient”), 17% (n = 228) was predominantly bottle fed and exhibited RWG (“Not Resilient”), and 49% (n = 658) was not predominantly bottle fed (“Low Risk”). Significant predictors of resilience to RWG were greater gestational age (P = 0.042) and weight (P \u3c 0.001) at birth, lower frequency of adding cereal to the bottle (P = 0.022), lower frequency of infant-led bottle-emptying (P = 0.047), and greater frequency of maternal encouragement of bottle-emptying (P = 0.002). Conclusions: Associations between bottle-feeding and RWG may be moderated by infant characteristics and maternal feeding practices. The present study highlighted several characteristics of predominantly bottle-fed infants who were resilient to RWG, but further research is needed to identify a broader array of key targets for future intervention efforts

Interpreting and acting upon home blood pressure readings: A qualitative study

This article is made available through the Brunel Open Access Publishing Fund. Copyright @ 2013 Vasileiou et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: Recent guidelines recognize the importance of home blood pressure monitoring (HBPM) as an adjunct to clinical measurements. We explored how people who have purchased and use a home blood pressure (BP) monitor make sense of, and act upon, readings and how they communicate with their doctor about the practice of home monitoring. Methods: A qualitative study was designed and participants were purposively recruited from several areas in England, UK. Semi-structured in-depth interviews were conducted with 18 users of home BP monitors. The transcribed data were thematically analysed. Results: Interpretation of home BP readings is complex, and is often characterised by uncertainty. People seek to assess value normality using ‘rules of thumb’, and often aim to identify the potential causes of the readings. This is done by drawing on lay models of BP function and by contextualising the readings to personal circumstances. Based on the perceived causes of the problematic readings, actions are initiated, mostly relating to changes in daily routines. Contacting the doctor was more likely when the problematic readings persisted and could not be easily explained, or when participants did not succeed in regulating their BP through their other interventions. Most users had notified their doctor of the practice of home monitoring, but medical involvement varied, with some participants reporting disinterest or reservations by doctors. Conclusions: Involvement from doctors can help people overcome difficulties and resolve uncertainties around the interpretation of home readings, and ensure that the rules of thumb are appropriate. Home monitoring can be used to strengthen the patient-clinician relationship

The discursive construction of childhood and youth in AIDS interventions in Lesotho's education sector: Beyond global-local dichotomies

This is the post-print version of this article. The definitive, peer-reviewed and edited version of this article is published in Environment and Planning D,Society and Space 28(5) 791 – 810, 2010, available from the link below. Copyright @ 2010 Pion.In southern Africa interventions to halt the spread of AIDS and address its social impacts are commonly targeted at young people, in many cases through the education sector. In Lesotho, education-sector responses to AIDS are the product of negotiation between a range of ‘local’ and ‘global’ actors. Although many interventions are put forward as government policy and implemented by teachers in schools, funding is often provided by bilateral and multilateral donors, and the international ‘AIDS industry’—in the form of UN agencies and international NGOs—sets agendas and makes prescriptions. This paper analyses interviews conducted with policy makers and practitioners in Lesotho and a variety of documents, critically examining the discourses of childhood and youth that are mobilised in producing changes in education policy and practice to address AIDS. Focusing on bursary schemes, life-skills education, and rights-based approaches, the paper concludes that, although dominant ‘global’ discourses are readily identified, they are not simply imported wholesale from the West, but rather are transformed through the organisations and personnel involved in designing and implementing interventions. Nonetheless, the connections through which these discourses are made, and children are subjectified, are central to the power dynamics of neoliberal globalisation. Although the representations of childhood and youth produced through the interventions are hybrid products of local and global discourses, the power relations underlying them are such that they, often unintentionally, serve a neoliberal agenda by depicting young people as individuals in need of saving, of developing personal autonomy, or of exercising individual rights.RGS-IB

Understanding Real World Indoor Scenes With Synthetic Data

Scene understanding is a prerequisite to many high level tasks for any automated intelligent machine operating in real world environments. Recent attempts with supervised learning have shown promise in this direction but also highlighted the need for enormous quantity of supervised data- performance increases in proportion to the amount of data used. However, this quickly becomes prohibitive when considering the manual labour needed to collect such data. In this work, we focus our attention on depth based semantic per-pixel labelling as a scene understanding problem and show the potential of computer graphics to generate virtually unlimited labelled data from synthetic 3D scenes. By carefully synthesizing training data with appropriate noise models we show comparable performance to state-of-the-art RGBD systems on NYUv2 dataset despite using only depth data as input and set a benchmark on depth-based segmentation on SUN RGB-D dataset