Showing papers by "Hong Kong Polytechnic University published in 1987"
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TL;DR: Washing of leaf samples reduced the levels of Cu, Mn, Zn and Fe contamination and suggested that the source of heavy metal pollution was mainly due to aerial deposition from motor vehicles.
62 citations
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48 citations
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01 Sep 1987TL;DR: In this article, the vertical-fin array's geometrical parameters, corresponding to achieving maximum rates of heat loss, were deduced for a polished, duralumin and extended-plate, heat exchanger through air.
Abstract: Steady state rates of free-convective, conductive and radiative heat transfer from a polished, duralumin and extended-plate, heat exchanger through air have been measured. When its vertical base was maintained at 40.0 (±0.2) K above the local air temperature (=15.5 ± 0.4°C) in the laboratory, optimal values of the vertical-fin array's geometrical parameters, corresponding to achieving maximum rates of heat loss, were deduced. For a base of width 190 mm and length 250 mm, the optimal uniform separation between 3 mm thick fins rose from 9.5 to 11.1 mm as the fin protrusion was decreased from 90 to 30 mm: it was almost independent of temperature within the range considered. For a base of width 190 mm and length 500 mm, the optimal uniform thickness for fins of 60 mm protrusion rose from 1.5 to 3.6 mm as the fin separation was increased from 15 to 55 mm, the optimal fin thickness being almost invariant with respect to changes in the fins' base temperature.No generalized quantitative recommendations emerge fro...
25 citations
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TL;DR: In this article, the scattering form factor I(q,ω) for magnetic excitations of a d=3 simple cubic antiferromagnet within the effective medium approximation (EMA) was calculated.
Abstract: Site‐diluted antiferromagnets with short‐range interactions can serve as a model magnetic percolation system. A length scale ξ exists such that for length scales (1/q)>ξ the structure is continuous (hydrodynamic limit), and the magnetic excitations are antiferromagnetic magnons, with a stiffness constant which depends critically upon the magnetic concentration. For length scales (1/q)<ξ, the structure is fractal, and the magnetic excitations are fractons, with a characteristic dispersion law. The fracton excitations are (strongly) spatially localized. The magnons are expected to be extended in the very long length scale limit, with the possibility of Anderson (weak) localization for length scales longer than ξ. The magnetic excitations cross over from magnon to fracton at an energy ωc∝ξ−[1+(θ/2)], where θ is the anomalous diffusion exponent. We have calculated the scattering form factor I(q,ω) for magnetic excitations of a d=3 simple cubic antiferromagnet within the effective medium approximation (EMA), a...
16 citations
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TL;DR: In this paper, the effects of varying the fin thickness on the steady-state rate of heat loss from the fin array have been measured experimentally for free-convection conditions.
11 citations
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TL;DR: In this paper, the effect of vertical partitioning on natural convection in air-filled rectangular enclosures was studied and it was found that placing a partition midway between the vertical walls of an enclosure produces the greatest reduction in heat trans fer and often compares favorably with fully insulating the enclosure with a porous material.
Abstract: This work is a study on the effect a vertical partition has on steady-state natural convection in air-filled rectangular enclosures. A finite difference scheme was used to solve the governing equations. Computed Nusselt numbers are presented as a func tion of the governing parameters. It was found that placing a partition midway be tween the vertical walls of an enclosure produces the greatest reduction in heat trans fer and often compares favorably with fully insulating the enclosure with a porous material.
9 citations
01 Aug 1987
4 citations
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TL;DR: A detail description of the surface vorticity method and its applications in calculations of two-dimensional potential flow around complicated objects of arbitrary shape and attractive graphic output of velocity field, pressure field, and stream function plots are provided.
2 citations
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17 Feb 1987TL;DR: In this article, a general light intensity expression in terms of Stokes vectors is derived which can be used to calculate the light-intensity distribution in holographic Photoelastioity.
Abstract: A general light-intensity expression in terms of Stokes vectors is derived which can be used to calculate the light-intensity distribution in holographic Photoelastioity. It is shown that this expression is applicable to either conventional holophotoelasticity or polarization holophotoelasticity and can be applied to single-or double-exposure holophotoelasticity. Some typical examples are presented.