Compartment tests of polyurethane foam seating assemblies

Data from compartment tests of polyurethane foam seating assemblies are reported. Results show that the behavior of such assemblies during fires is strongly dependent on the type and position of interliners and upholstery fabrics. An incidental comparison of peak rate of heat release obtained in a compartment test with a predictive model equation is made and selected data from the tests are presented.     

The development of macrolayer thickness of water in the pool boiling regime

ABSTRACT

The main purpose of this study is to analyse the phenomenon of pool boiling in water over a horizontally placed copper tube heater of 28?mm diameter. The experiment has been carried out to observe the bubble growth and departure characteristics for the heat flux range up to 40,000?W/m². The entire process is being recorded by a digital camera at different time intervals. The measured parameters have been used to determine the initial layer thickness, macro layer thickness and critical heat flux and validated with models proposed in the literature.     

Results of evaluation of the strength of concrete placed in the shafts of cast-in-place piles

Conclusions 1. Application of the method of underwater concreting with the use of a container is inexpedient in connection with the presence of a large number of flaws detected in the shafts of cast-in-place piles formed by this method; concreting of holes by the VAT method is preferable.2. The strength of concrete in the shafts of cast-in-place piles increases, reaching a maximum at a depth of 0.4–0.5 the length of the shaft. Variation in strength along the shaft is explained primarily by the percentage of coarse aggregate contained in the concrete.3. The quality of pile concrete should be monitored during all stages of pile installation, and, primarily during the stage of concreting, i.e., when there is a chance of correcting an observed defect.All-Union Institute for the Design and Planning of Health Resorts. Scientific-Research Institute of Foundations and Underground Structures. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 14–17, September–October, 1976.     

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.     

Trace-metal concentrations in normal human liver: methods to cope with marked variability

Concentrations of trace elements in human tissues characteristically vary widely, and the distributions of most concentrations are skewed to the right. Examination of some of the factors which contribute to the marked variability and skewness of the concentrations revealed that: (1) distributions of concentrations are satisfactorily normal (Gaussian) after logarithmic transformation, (2) ash weight is the best frame of reference in which to report results, (3) the distributions of metal concentrations are not further normalized by adjustments which assume that tissue lipid or collagen contains a fixed fraction of the metal found in the parenchyma, and (4) the choice of sample site within the liver is of minimal significance.     

Combined nitrification/denitrification in a membrane reactor

An ever stricter legislation regulating wastewater leads to an increasing demand for biological treatment plants which are able to selectively eliminate nitrogen from wastewaters with a high influent concentration, even when operating in partial influent mode. A membrane-tube-module (MSM) reactor (Membran-Schlauch-Modul-Reaktor) was constructed and realized in the IUV at the University of Bremen. The present approach makes use of all the various layers of the whole biofilm, enabling nitrification and denitrification processes to run simultaneously in one and the same biofilm under optimized conditions. The biological degradation capacity of the system was first successfully tested with synthetic wastewater, and subsequently in a real application with effluents from a recycling of animal carcasses plant and from a coke-oven plant. A mathematical model was devised which describes this biofilm system. The resulting equations were solved by means of the simulation software AQUASIM.     

The bacterial population of piggery-waste anaerobic digesters

A survey was made of the anaerobic and facultatively anaerobic bacteria present in piggery waste, digesting piggery waste and domestic anaerobic sludge sludge used to start a piggery waste digester. An influence of the input waste was shown in that streptococci, the predominant facultatively anaerobic bacteria in the piggery waste, were the predominant bacteria in the digesting waste, and they replaced Enterobacter, predominant in the domestic sludge, when a piggery waste digestion had been established from this latter material. Cellulolytic or methanogenic bacteria could not be detected in the piggery waste but populations of these, and other hydrolytic bacteria, became established at different times during the buildup of digestion by gradual addition of piggery waste to water. The bacteria concerned in degradation of the waste constituents were all anaerobes.Production of methane from H₂/CO₂, formate and butyrate could be detected in mixed cultures from dilutions of digester contents, but the only methanogenic bacterium that could be isolated in pure culture was Methanobacterium formicicum, which uses H₂/CO₂ or formate only.     

Monitoring and kinetic study of ammonia oxidation using dissolved oxygen electrode and NAD(P) H fluorometer

The ammonia oxidation of a mixed culture enriched from a wastewater treatment plant sludge was monitored by a DO probe and a nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) fluorometer. Under fixed aeration, DO reflected ammonia oxidation effectively. According to the DO profiles and the total ammonia concentrations analyzed experimentally, the ammonia oxidation kinetics of the enriched culture was determined. The ammonia oxidation rate was found sensitive to pH, especially at low total ammonia concentrations. At high concentrations of total ammonia, the maximum ammonia oxidation rate occurred at pH 7.6+/-0.1. At low concentrations, the pH sensitivity intensified significantly and the apparent optimal pH shifted higher with decreasing total ammonia concentrations, because NH3 molecules were the true substrate for ammonia oxidation and more NH4+ ions were converted to NH3 molecules at higher pH. The ammonia oxidation kinetics was therefore developed according to the concentration of NH3 molecules, instead of the commonly used total ammonia concentration. The kinetics followed Michaelis-Menten behavior for both DO and NH3 concentration: the maximum rate was 16.7+/-0.7 mg NH3-N/(g TSS-h) and the Michaelis constants for DO and NH3 were (14+/-2)% air saturation and (4.4+/-0.4) x 10(-2) (mg NH3-N/L), respectively. It was also concluded from the study that with or without exogenous organic substances, the NAD(P)H fluorescence of the enriched nitrifying culture was undetectable. The fluorescence did not respond to addition or depletion of substrate (ammonia, glucose, or acetate), change between aerobic and anaerobic conditions, or even KCN addition to kill the culture.     

Prediction of the effectiveness of rolling dynamic compaction using artificial neural networks and cone penetration test data

Rolling Dynamic Compaction(RDC),which is a ground improvement technique involving non-circular modules drawn behind a tractor,has provided the construction industry with an improved ground compaction capability,especially with respect to a greater influence depth and a higher speed of compaction,resulting in increased productivity. However,to date,there is no reliable method to predict the effectiveness of RDC in a range of ground conditions. This paper presents a new and unique predictive tool developed by means of artificial neural networks(ANNs) that permits a priori prediction of density improvement resulting from a range of ground improvement projects that employed 4-sided RDC modules;commercially known as"impact rollers". The strong coefficient of correlation(i.e. R0.86) and the parametric behavior achieved in this study indicate that the model is successful in providing reliable predictions of the effectiveness of RDC in various ground conditions.     

Lead contamination in tap water of households with children in Lower Saxony, Germany

Lead has numerous acute and chronic adverse effects on human beings. This is especially true for infants and children. The main path of lead ingestion in children can be different according to housing and living situation. The intake of lead through drinking water is commonly due to metal corrosion. The users plumbing can be an important factor. In recent years, many lead pipes in Germany have been replaced by pipes made of an alternative material. The aim of this study is to assess the present state of drinking water contamination and the resulting exposure of infants to lead. For this purpose mothers of new-born babies were offered a free examination of their drinking water. After a written declaration of consent had been obtained and after the infant in question had reached an age of 3 months, a stagnation sample of cold tap-water after overnight stagnation together with a random daytime sample was obtained from the family. The collected samples were analysed by atomic absorption spectrometry for their lead concentration. In total, 1485 samples from households were collected. Of the 1434 stagnation samples, 3.1% had lead concentrations greater than 0.01 mg/l (recommended limit of the WHO) and 0.6% had concentrations above the limit of the German drinking water regulation (0.04 mg/l). The values for the 1474 random daytime samples were 2.1% above 0.01 mg/l and 0.2% greater than 0.04 mg/l, respectively. By region, the areas Bovenden, Friedland, Duderstadt, Northeim and Rosdorf were particularly affected. The highest measured concentrations of lead in the stagnation samples were 0.11 mg/l and 0.15 mg/l in the random daytime samples, respectively.