1,722,662 research outputs found
In reply: Comparing videolaryngoscope and direct laryngoscope use for nasotracheal intubation in patients with manual in-line stabilization
No full textGRAPH-THEORETIC HEURISTICS FOR UNEQUAL-SIZED FACILITY LAYOUT PROBLEMS
No full textWe consider the unequal-sized facility layout problem with the objective of minimizing total transportation distance. The total transportation distance is defined as the sum of products of flow amounts and rectilinear distances between facilities, where flow amount represents the number of trips per time period between facilities, In the layout problem, it is assumed that shapes of facilities are not fixed and that there is no empty space between facilities in the layout. We propose new graph theoretic heuristics for the problem, In the heuristics, an initial layout is obtained by constructing a planar adjacency graph and then the solution is improved by changing the adjacency graph (not the physical layout), Therefore, these heuristics do not need an initial layout in advance, and sizes and locations of facilities do not have to be considered in the improvement procedure. Computational results showed that the proposed algorithms gave better solutions than those from CRAFT, which is one of the most popular algorithms for unequal-sized facility layout problems
Effect of tube alignment on the heat/mass transfer from a plate fin and two-tube assembly: naphthalene sublimation results
No full textFlow and heat/mass transfer in a plate fin and two-tube assembly is examined using the naphthalene sublimation technique. The examined parameter is the offset of two-tube centers to tube diameter ratio s/D for two Reynolds numbers Re-D: 1770 and 2660. The local heat/mass transfer coefficient is always large at the leading edge of the plate and also in front of the tube. The horseshoe vortex formed in front of the first tube increases the local heat/mass transfer rate not only around the first tube itself but also around the second tube. The total heat/mass transfer rate from the plate increases with s/D and it reaches a saturation beyond s/D = 0.5. Similar behavior is observed for the pressure drop, showing that s/D congruent to 0.5 is the optimal offset for the tested range. When the Reynolds number is as high as 2660, the effect of tube offset is significant, so that the total heat/mass transfer rate from the plate for the two-row tube case is larger than that for a single tube case. (C) 2003 Elsevier Science Ltd. All rights reserved.This work has been supported by the Critical Technology of the Ministry of Science and Technology, Korea
Scattering of plane acoustic waves by a transversely isotropic cylindrical shell - application to material characterization
No full textScattering of obliquely incident plane acoustic wave by an air-filled, transversely isotropic cylindrical shell immersed in water is investigated theoretically and experimentally. The normal mode expansion technique is employed for analyzing the scattering field, and then resonance modes of the shell appearing in modal scattering form functions are identified performing the resonance scattering analysis. Dispersion curves for Sholte-Stoneley, SH and Lamb waves are obtained and their characteristics are interpreted. Calculated backscattering and resonance spectra as well as dispersion curves are compared with those from ultrasonic experiments for two composite samples having the same nominal composition but fabricated under different conditions. Sensitive change of the dispersion curves is observed for both normal and oblique incidences, which demonstrates the feasibility of systematic inverse evaluation of damage or elastic constants of the composite shell using data from the acoustic scattering measurements. (C) 2003 Elsevier Ltd. All rights reserved
Dependence of spraying performance on the internal flow pattern in effervescent atomizers
No full textThe effect of the flow patterns inside the mixing chamber on the atomization performance of large-orifice (> 1.2 mm) effervescent atomizers for the low injection pressure range (< 4 bar) was examined experimentally. The transparent mixing chamber has a rectangular cross section (9 mm x 2 mm). The parameters tested were the air/liquid ratio (ALR), injection pressure, and the nozzle orifice diameter. Three different flow regimes were observed: bubbly, annular, and intermittent flows. In the bubbly flow regime, the discharged air/liquid mixture disintegrates into drops through the processes of bubble expansion and ligament breakup. On the other hand, in the annular flow regime, the liquid annulus disintegrates into fine drops by aerodynamic interaction due to high relative velocity between the core gas and the liquid film. In the intermittent flow regime, the bubble expansion/ligament disintegration and the annulus disintegration modes appear alternately. Transition criteria between the two-phase flow patterns within the mixing chamber are proposed based on the drift flux model. Finally, a drop size correlation encompassing all those flow regimes is proposed
Flow Visualization and Measurement of Pressure Drop in a Plate Fins/Circular Tube Assembly
No full textA Parametric Study on the Thermal Fatigue Reliability of Flip Chip Solder Joints in Electronic Packaging
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