The spread of fire in corridors

Full- and quarter-scale experimental fires in corridor-room assemblies, using various combinations of floor, wall, and ceiling lining materials, yielded some interesting results. Between the small-and large-scale tests, there were marked differences in the relative effects of floor coverings and ceiling linings. Note: This paper is a contribution from the Division of Building Research, National Research Council of Canada and is published with the approval of the Director of the Division.     

The impact of using chilled water storage systems on the performance of air cooled chillers in Kuwait

In the air conditioning (AC) industry chilled water storage (CWS) systems are one form of cool thermal storage technology that can be used to time shift the electrical load of the system from the peak day periods to off peak night time periods. In this paper the data for the actual exported and generated electrical energy obtained for the power stations in Kuwait has been used to estimate the electrical energy consumption and the peak electrical load of AC systems. Since the chiller in an air cooled AC system represent more than 75% of the total electrical power consumed by an AC system during the peak demand period, the impact of using CWS systems with alternative operating strategies including partial (load levelling), partial (demand limiting) and full load has been investigated. In our conclusions we estimate that approximately 45% of the total annual exported electrical energy is consumed solely by AC systems as a result of the very high ambient temperatures occurring between March and October. Furthermore, it is estimated AC systems represent about 62% of the peak electrical load. The results demonstrate that CWS can reduce the peak electrical load of a chiller in an air cooled AC system by up to 100% and reduce the nominal chiller size by up to 33% depending upon the operating strategy adopted. This is achieved with only a 4% increase in power consumption of the chiller for all CWS strategies except for full storage where the energy consumption actually decreases by approximately 4%.     

A digital wind gust recorder

The instrument was a byproduct of an undergraduate final year project on wind power which was carried out by the Department of Mechanical Engineering of the University of Liverpool.The windmill test site was on an exposed, rocky island where there was no history of weather recording but a long tradition of violent winds.Field experience during the winter months suggested that corrosion fatigue arising from wind buffeting and salt spray would rank equally with maximum wind pressure as criteria of failure and if modern materials, so convenient for forming aerodynamic surfaces, were to be used then limited life concepts would need to be considered. This called for more knowledge of wind variations at the test site. A complete wind spectrum taken on chart recording instruments would have been ideal but since such such refined devices were not available the instrument to be described was designed.The only wind measuring instrument which was available was a rotating cup anemometer. This supplied an alternating voltage proportional to its rotational speed. It also operated a gear driven microswitch which could give an integrated “miles of wind” reading on an electromagnetic counter.Briefly the e.m.f. generated by the anemometer (Fig. 1) was matched against a pre-set voltage corresponding to the required gust velocity. When this was exceeded an appropriate counter was operated. Only the rising e.m.f. was significant. The subsequent fall was ignored. Initially three stages were incorporated which reported the gusts rising through forty, fifty and sixty knots, respectively. These recorded on separate counters. All basic settings were based on pitot-static speed determinations in a wind tunnel.     

Combined biological and ozone treatment of log yard run-off

Batch biological treatment of log yard run-off reduced biochemical oxygen demand (BOD), chemical oxygen demand (COD) and tannin and lignin (TL) concentration by 99%, 80%, and 90%, respectively. Acute (Microtox) toxicity was decreased over treatment, from an initial EC50 of 1.83% to a value of 50.4% after 48 h of treatment. Kinetics of biodegradation were determined using respirometry and fitted using the Monod and Tessier model. For the Monod model the maximum substrate uptake rate, and Ks values determined were 0.0038 mg BOD/mgVSS min, and 1.4 mg/L, respectively. The efficacy of ozone as a pre- and post- biological treatment stage was also assessed. During ozone pretreatment, TL concentration and acute toxicity were rapidly reduced by 70% and 71%, respectively. Pre-ozonation reduced BOD and COD concentration by < 10%, however a larger fraction of residual COD was non biodegradable after ozonation. Biologically treated effluent was subjected to ozonation to determine whether further improvements in effluent quality could be achieved. A reduction in COD and TL concentration was observed during ozonation, however no further improvement in toxicity was observed. Ozonation increased BOD by 38%, due to conversion of COD to BOD.     

Enhancement of bond strength for epoxy-coated rebar using river sand

In this paper, improvement of bond strength for epoxy-coated rebars is studied. Although the epoxy-coated rebar is well accepted as an alternative corrosion prevention method in engineering practice, it still suffers from its poor bond performance, which requires modification of design parameters such as development length and splice length. Following our previous study [Proceedings of the Third Structure Engineering Conference (1996) 651–659], it is proposed to mix the river sand in the epoxy to improve the bond strength of epoxy-coated rebar. Specimens of several sizes of river sand and sand/epoxy weight ratios were studied. The single-rebar pullout test was performed to examine the bond strength. The open circuit potential method and the linear DC polarization method were conducted for corrosion rate measurements to ensure for keeping the merit of epoxy-coated rebar, i.e. the ability of corrosion. Experimental results show that the proposed method is very promising.     

Heavy metals in maternal and cord blood

Heavy metal concentrations have been determined in maternal and cord blood samples collected from mothers in the age group 20-25 years with full-term neonates (37-40 weeks). The concentrations of Pb, Cd, Cu and Zn were found to be low in cord blood as compared to mother's blood and the ratio between cord blood and maternal blood for the respective elements was found to be approximately 0.80, 0.86, 0.47 and 0.40. On the other hand, the concentrations of Fe and Mg in the mother's blood were found to be lower than those in the cord blood. Prenatal exposure to lead in Mumbai, though low (5.1 microg/dl), is approximately 2-3 times higher than that observed in Canada or Italy. A strong correlation (r = 0.79) between the maternal and cord blood lead levels has been observed during the present study.     

Organochlorines in egg samples from Norwegian birds of prey: congener-, isomer- and enantiomer specific considerations

The content of chlorinated persistent organic pollutants was determined in a total of 44 egg samples from 8 different raptor species collected throughout Norway in the period 1991-1997. The content of 8 chlorinated bornanes, 9 chlorinated pesticides, and 15 polychlorinated biphenyl congeners (PCB) were determined. The highest average concentrations for PCB were found for eggs from White-tailed Sea Eagle and Peregrine Falcon (average sum PCB concentration: 8.9 and 9.1 microg/g wet weight (w.w.), respectively). Merlin and Sparrowhawk eggs were the highest contaminated with chlorinated pesticides (average sum pesticide concentration: 3.0 and 4.3 microg/g w.w.). For the first time, the content of chlorobornanes was determined in Norwegian birds of prey eggs. However, only minor contamination compared to PCBs and conventional chlorinated pesticides was found. The highest sum concentration was determined for White-tailed Sea Eagle eggs (0.09 microg/g w.w.). No chlorobornane contamination was found in Osprey and Merlin eggs. No spatial and regional specific trends or pattern distribution were found for organochlorine contamination in the egg samples analysed. In order to gain information about enantiomer specific bioaccumulation and biotransformation capacity of the organism, enantioselective analyses was performed for the chiral contaminants trans-chlordane, oxy-chlordane and the chlorobornane B9-1679 (Parlar #50). Indications for species-dependent deviation from the racemic distribution (enantiomeric ratio = 1) were found. Peregrine Falcon and Merlin eggs were characterised with an extremely high enantiomeric excess of the (-)-trans-chlordane (enantiomeric ratio (ER) <0.01). For Golden Eagle, Goshawk and Sparrowhawk eggs, the ERs were between 0.1 and 0.22 demonstrating also here that the (-)-trans-chlordane was the most abundant enantiomer. For the distribution of oxy-chlordane and B9-1679 enantiomers no species-dependent differences were found. For all species the ER values between 0.3 and 0.8 were determined. Thus, also for oxy-chlordane and B9-1679, the (-)-enantiomers are the most dominating stereoisomers in the birds of prey eggs analysed.     

Toxic metals in the atmosphere in Lahore, Pakistan

Aerosol mass (PM₁₀ and PM_2.5) and detailed elemental composition were measured in monthly composites during the calendar year of 2007 at a site in Lahore, Pakistan. Elemental analysis revealed extremely high concentrations of Pb (4.4 μg m^− 3), Zn (12 μg m^− 3), Cd (0.077 μg m^− 3), and several other toxic metals. A significant fraction of the concentration of Pb (84%), Zn (98%), and Cd (90%) was contained in the fine particulate fraction (PM_2.5 and smaller); in addition, Zn and Cd were largely (≥ 60%) water soluble. The 2007 annual average PM₁₀ mass concentration was 340 μg m^− 3, which is well above the WHO guideline of 20 μg m^− 3. Dust sources were found to contribute on average (maximum) 41% (70%) of PM₁₀ mass and 14% (29%) of PM_2.5 mass on a monthly basis. Seasonally, concentrations were found to be lowest during the monsoon season (July-September). Principle component analysis identified seven factors, which combined explained 91% of the variance of the measured components of PM₁₀. These factors included three industrial sources, re-suspended soil, mobile sources, and two regional secondary aerosol sources likely from coal and/or biomass burning. The majority of the Pb was found to be associated with one industrial source, along with a number of other toxic metals including As and Cr. Cadmium, another toxic metal, was found at concentrations 16 times higher than the maximum exposure level recommended by the World Health Organization, and was concentrated in one industrial source that was also associated with Zn. These results highlight the importance of focusing control strategies not only on reducing PM mass concentration, but also on the reduction of toxic components of the PM as well, to most effectively protect human health and the environment.     

Measurement of the intrinsic process zone in rock using acoustic emission

Laboratory specimens with a smooth boundary (no notch) were fabricated from four different rock types (grain sizes from 0.1–10 mm) and were tested in three-point bending. The locations of acoustic emission that occurred around peak load were used to characterize the dimensions of the region of localized microcracking, the so-called intrinsic process zone. The size of this zone was found to vary significantly between the rock types, but was not found to vary significantly for different size beams of the same material. An approximately linear relation was found between the width of the intrinsic process zone and the logarithm of the grain size. An explanation of size effect evolves naturally by considering the intrinsic process zone as a material characteristic. Two different models were used to analyze stress at failure. The first treated the intrinsic process zone as a mathematical crack, an infinite stress raiser, from which a K_IC value was calculated. The second model assumed the intrinsic process zone was a cohesive notch, a finite stress raiser, from which the theoretical tensile strength was defined. The second method seemed somewhat better at predicting size effect on nominal peak stress.     

Microanalysis of anionic surfactants in waste water by infrared spectroscopy

Infrared spectroscopy was applied to identify and determine microamounts of anionic surfactants contained in sewage or river waters. The surfactants tested were linear alkylbenzene sulfonate (LAS), branched alkylbenzene sulfonate (ABS), alpha olefine sulfonate (AOS), fatty alcohol sulfate (AS) and fatty alcohol ethoxy sulfate (AES).Anionic surfactants in waters were extracted by chloroform as methylene blue complexes and sulfate type surfactants, i.e. AS and AES were then removed by subsequent hydrolysis. Residual sulfonate type surfactants were first released from methylene blue complexes by ion exchange technique and then changed to sulfonyl chloride derivatives for infrared spectroscopy. Key bands for the identification of sulfonate type surfactants are 640, 618 and 524 cm⁻¹ for LAS, ABS and AOS, respectively. Sulfate type surfactants was calculated from the difference of methylene blue active substance contents before and after hydrolysis.