Performance of Diesel Engines at High Altitudes

Problems are encountered when conventional, normally aspirated diesel engines are operated at high altitudes. The results of a study carried out at the Indian Institute of Petroleum both on stationary and automotive diesel engines covering the principal problems of power loss and poor thermal efficiency are presented in this paper

Outcome of fistulotomy Vs fistulectomy in management of fistula in Ano: A prospective study

AIMS & OBJECTIVES: To compare fistulotomy Vs fistulectomy in management of low anal fistulas IN Chengalpattu Medical College, Chengalpattu. METHODS: 60 patients with low anal fistulas admitted in our hospital during one year period were randomly divided into two groups.First group underwent fistulotomy and Second group was treated using fistulectomy. Postoperative Pain ,bleeding and wound healing among the 2 groups were assessed and statistically analysed. RESULTS & CONCLUSIONS: Among the 2 groups, group which underwent fistulotomy showed better wound healing compared to fistulectomy group. It is concluded that fistulectomy has no advantage over fistulotomy in postoperative period and short term follow up for patients with simple low anal fistula

Lie Group Analysis of Natural Convection Heat and Mass Transfer in an Inclined Surface

Natural convection heat transfer fluid flow past an inclined semiinfinite surface in the presence of solute concentration is investigated by Lie group analysis. The governing partial differential equations are reduced to a system of ordinary differential equations by the translation and scaling symmetries. An exact solution is obtained for translation symmetry and numerical solutions for scaling symmetry. It is found that the velocity increases and temperature and concentration of the fluid decrease with an increase in the thermal and solutal Grashof numbers. The velocity and concentration of the fluid decrease and temperature increases with increase in the Schmidt number

Influence of Transverse Magnetic Field on Microchannel Heat Sink Performance

The aim of the present numerical investigation is to analyze the effects of transverse magnetic field on heat transfer and fluid flow characteristics in a rectangular microchannel heat sink (MCHS). The effects of Hartmann number, channel aspect ratio, total channel height and total channel width on heat transfer and fluid flow characteristics are widely investigated. The governing equations for three-dimensional steady, laminar flow and conjugate heat transfer of a microchannel are solved using the finite volume method. The obtained results are discussed with various combinations of pertinent parameters involved in the study. The results reveal that magnetic field can enhance the thermal performance of the MCHS but it is accompanied with a slight increase in pressure drop

Experimental Investigation on Mechanical and Turning Behavior of Al 7075/ x

The present research work involves the study of AA 7075-TiB2-Gr in situ composite through stir casting route. This in situ method involves formation of reinforcements within the matrix by the chemical reaction of two or more compounds which also produces some changes in the matrix material within the vicinity. Titanium Diboride (TiB2) and graphite were the reinforcement in a matrix of AA 7075 alloy. The composite was prepared with the formation of the reinforcement inside the molten matrix by adding salts of Potassium Tetrafluoroborate (KBF4) and Potassium Hexafluorotitanate (K2TiF6). The samples were taken under casted condition and the properties of the composite were tested by conducting characterization using X-ray diffraction (XRD), hardness test, flexural strength by using three-point bend test, scanning electron microscope (SEM), optical microstructure, grain size analysis, and surface roughness. It was found that good/excellent mechanical properties were obtained in AA 7075-TiB2-Gr reinforced in situ hybrid composite compared to alloy due to particulate strengthening of ceramic particles of TiB2 in the matrix. Further, Al 7075-3% TiB2-1% Gr hybrid in situ composite exhibited improved machinability over the alloy and composites due to self-lubricating property given by the Gr particles in the materials

The Impact of 18 Ancestral and Horizontally-Acquired Regulatory Proteins upon the Transcriptome and sRNA Landscape of Salmonella enterica serovar Typhimurium

Article Authors Metrics Comments Media Coverage Abstract Author Summary Introduction Results and Discussion Materials and Methods Supporting Information Acknowledgments Author Contributions References Reader Comments (0) Media Coverage (0) Figures Abstract We know a great deal about the genes used by the model pathogen Salmonella enterica serovar Typhimurium to cause disease, but less about global gene regulation. New tools for studying transcripts at the single nucleotide level now offer an unparalleled opportunity to understand the bacterial transcriptome, and expression of the small RNAs (sRNA) and coding genes responsible for the establishment of infection. Here, we define the transcriptomes of 18 mutants lacking virulence-related global regulatory systems that modulate the expression of the SPI1 and SPI2 Type 3 secretion systems of S. Typhimurium strain 4/74. Using infection-relevant growth conditions, we identified a total of 1257 coding genes that are controlled by one or more regulatory system, including a sub-class of genes that reflect a new level of cross-talk between SPI1 and SPI2. We directly compared the roles played by the major transcriptional regulators in the expression of sRNAs, and discovered that the RpoS (σ38) sigma factor modulates the expression of 23% of sRNAs, many more than other regulatory systems. The impact of the RNA chaperone Hfq upon the steady state levels of 280 sRNA transcripts is described, and we found 13 sRNAs that are co-regulated with SPI1 and SPI2 virulence genes. We report the first example of an sRNA, STnc1480, that is subject to silencing by H-NS and subsequent counter-silencing by PhoP and SlyA. The data for these 18 regulatory systems is now available to the bacterial research community in a user-friendly online resource, SalComRegulon

RNA-seq Brings New Insights to the Intra-Macrophage Transcriptome of Salmonella Typhimurium.

Salmonella enterica serovar Typhimurium is arguably the world's best-understood bacterial pathogen. However, crucial details about the genetic programs used by the bacterium to survive and replicate in macrophages have remained obscure because of the challenge of studying gene expression of intracellular pathogens during infection. Here, we report the use of deep sequencing (RNA-seq) to reveal the transcriptional architecture and gene activity of Salmonella during infection of murine macrophages, providing new insights into the strategies used by the pathogen to survive in a bactericidal immune cell. We characterized 3583 transcriptional start sites that are active within macrophages, and highlight 11 of these as candidates for the delivery of heterologous antigens from Salmonella vaccine strains. A majority (88%) of the 280 S. Typhimurium sRNAs were expressed inside macrophages, and SPI13 and SPI2 were the most highly expressed pathogenicity islands. We identified 31 S. Typhimurium genes that were strongly up-regulated inside macrophages but expressed at very low levels during in vitro growth. The SalComMac online resource allows the visualisation of every transcript expressed during bacterial replication within mammalian cells. This primary transcriptome of intra-macrophage S.-Typhimurium describes the transcriptional start sites and the transcripts responsible for virulence traits, and catalogues the sRNAs that may play a role in the regulation of gene expression during infection

Heat retention analysis with thermal encapsulation of powertrain under natural soak environment

This paper investigates high fatality modelling of vehicle heat transfer process during natural soak environment and heat retention benefits with powertrain encapsulations. A coupled computer-aided-engineering (CAE) method utilising 3D computational-fluids-dynamics (CFD) and transient thermal modelling was applied to solve buoyancy-driven convection, thermal radiation and conduction heat transfer of vehicle structure and fluids within. Two vehicle models with different encapsulation layouts were studied. One has engine-mounted-encapsulation (EME) and the other has additional vehicle-mounted-encapsulation (VME). Coupled transient heat transfer simulations were carried out for the two vehicle models to simulate their cool-down behaviours of 9 h static soak. The key fluids temperatures’ cool-down trajectories were obtained and correlated well with vehicle test data. Increased end temperatures were seen for both coolant and oils of the VME model. This provides potential benefits towards CO2 emissions reduction and fuel savings. The air paths and thermal leakages with both encapsulations were visualised. Reduced leakage pathways were found in the VME design in comparison with the EME design. This demonstrated the capability of embedded CAE encapsulation heat retention modelling for evaluating encapsulation designs to reduce fuel consumption and emissions in a timely and robust manner, aiding the development of low-carbon transport technologies

Numerical investigation of buoyancy-driven heat transfer within engine bay environment during thermal soak

This paper investigates transient heat transfer processes of a vehicle under-bonnet region during natural soak condition using computer aided engineering (CAE). Heat reserved within the engine bay is beneficial to the engine cold-start for potentially reductions in friction losses, CO2 emissions and fuel consumption. Buoyancy-driven convection, thermal radiation and conduction are key contributors to heat transfer processes of engine compartments during soak. In this study, a coupled transient 3D computational fluids dynamics (CFD) – heat transfer modelling method was studied in a passenger vehicle to simulate its 9 h cool-down behaviours. The developed CAE method was able to predict the temperature cool-down of the key fluids of good agreement with experiments. Potential air and heat leakage paths around the engine bay were identified. The flow development during the early stage (0–2 h) of the soak was vital to accurate prediction of the heat transfer coefficients for the heat retention modelling, where convection and radiation have played important parts. Optimum simulation strategy was obtained with reduced simulation time and good prediction accuracy. This further allows the integration of engine encapsulation design for optimising fuel consumption and emissions in a timely and robust manner, aiding the development of low-carbon transport technologies