Function Of Pool Size Research Articles

Effects of pool size and spacing on burning rate and flame height of two square heptane pool fires.

The interaction of multiple pool fires might lead to higher burning rate and flame height than single pool fire, raising the possibility of fire ignition and flame spread and increasing the risks to people, buildings and environment. To quantify the burning rate and flame height of multiple pool fires from the view of physical mechanism, this paper presents an experimental study on two identical square pool fires. Heptane was used as fuel. The pool size and spacing were varied. Results showed that both the burning rate and flame height change non-monotonically with spacing. From the view of air entrainment, a correlation for the flame height of two pool fires is developed involving pool size, spacing and the flame height of zero spacing. The comparison with experimental results shows that the developed correlation is suitable for two heptane or propane fires. A theoretical study based on energy balance at one of the pool surfaces is performed to evaluate the burning rate of two fires, which is finally expressed as a function of pool size, spacing, burning rate and the flame height of single fire. The proposed model is validated using the experimental and literature data, which presents a reasonable reliability.

A Bayesian Approach to Estimate OJD Prevalence From Pooled Fecal Samples of Variable Pool Size

This paper describes a Bayesian approach to prevalence estimation based on pooled samples that accommodates variation in pool size and adjusts for test imperfection. A logistic model was developed for pooled fecal culture (PFC) sensitivity as a function of pool size and a logistic mixed model for ovine Johne’s disease (OJD) prevalence as a function of covariates that were found significant in a recent OJD risk factor study conducted in Australia. Available data on these factors and prior information about prevalence and sensitivity were incorporated into a Bayesian model to estimate OJD prevalence from PFC data. Overall, posterior cohort OJD prevalence was estimated to be 0.16 (range of prevalences across cohorts 0.002 to 0.72). The average prevalence was higher in wethers than ewes. PFC sensitivities for pool sizes 10, 30 and 50 were estimated to be 0.91 (95% probability intervals 0.80, 0.96), 0.85 (0.80, 0.90) and 0.77 (0.65, 0.88), respectively. Posterior specificity of PFC was almost perfect though based primarily on the prior. Results suggest the Bayesian model successfully estimated the animal-level prevalence after accounting for variable pool size and imperfect test parameters. The method can be easily adapted for other conditions and diseases where pooled samples are collected. WinBugs code for the article is available online.

Predicting the emissive power of hydrocarbon pool fires

The emissive power ( E) of a flame depends on the size of the fire and the type of fuel. In fact, it changes significantly over the flame surface: the zones of luminous flame have high emittance, while those covered by smoke have low E values. The emissive power of each zone (that is, the luminous or clear flame and the non-luminous or smoky flame) and the portion of total flame area they occupy must be assessed when a two-zone model is used. In this study, data obtained from an experimental set-up were used to estimate the emissive power of fires and its behaviour as a function of pool size. The experiments were performed using gasoline and diesel oil as fuel. Five concentric circular pools (1.5, 3, 4, 5 and 6 m in diameter) were used. Appropriate instruments were employed to determine the main features of the fires. By superimposing IR and VHS images it was possible to accurately identify the luminous and non-luminous zones of the fire. Mathematical expressions were obtained that give a more accurate prediction of E lum, E soot and the average emissive power of a fire as a function of its luminous and smoky zones. These expressions can be used in a two-zone model to obtain a better prediction of the thermal radiation. The value of the radiative fraction was determined from the thermal flux measured with radiometers. An expression is also proposed for estimating the radiative fraction.

Performance on Word-Fluency Tasks as a Function of Task Variables

bigrams, were manipulated. It was found, as suspected, that there were differences in average productivity associated with different bigrams. Moreover, this difference in difficulty could be predicted in a rank-order sense given a knowledge of: (a) the pool size or number of English words actually beginning with a specified bigram, and (b) whether the bigram was composed of a vowel followed by a consonant (VC) or a consonant followed by a vowel (CV). Word production increased as a function of pool size and was generally greater for bigrams of the CV type. An interaction of the two variables, however, indicated that among bigrams of the VC type, production increased as a function of pool size between low and medium pools, but not between medium and great pools. Thus, for the VC bigrams, an increase in pool size beyond an intermediate level failed to facilitate production. The purpose of the research reported here was to explore the generality of these findings. First, an attempt was made to replicate the study discussed above using a differently defined group of human beings as Ss. It was hypothesized that the magnitude of mean responses to the various bigrams would decrease with a decrease in the age or grade of Ss, but that the relationships among the bigrams would remain the same. Subsequently a second word-fluency task was introduced for examination. The first-and-last-letter (FLL) task required that Ss write all the words they could that began and ended according to the letter combination given. It was predicted that production would be positively related to consonant structure of the given first letter and the pool size of the first-and-last-letter combination.