Convection in fluid overlying porous layer : an application to Hall-Heroult cell

Finite-element method is used to predict the buoyancy-driven convection in a horizontal layer of fluid (aluminum melt) overlying a porous layer (cathode) saturated with the same fluid. This work aims to compare the Hall–Héroult process in electrolytic cell, where a layer of molten aluminum is reduced over the porous cathode surface. In this study, the physical system of the aluminum melt (fluid) and cathode (porous) together is considered as a composite system of fluid overlying porous layer. The main objective of this study to analyse the velocity components in thin fluid layer and its impact on a porous cathode surface if there is any. In addition, an externally imposed time-independent uniform magnetic field is used to analyse its influence on natural convective forces. The physical system of fluid overlying porous layer is analysed at different Hartmann, Darcy, and fluid-Rayleigh numbers for a fixed Prandtl number (Pr = 0.014). The predicted data show that the convective forces, caused by buoyancy-driven flow, are significant. It is shown that the velocity peaks moves toward the solid wall because of the presence of a magnetic field creating a stronger boundary-layer growth over the permeable cathode surface. The predicted results are plotted in terms of average Nusselt number and Darcy number to indicate the influence of pores and permeability on overall convective heat-transfer characteristics.

Natural convection in domed porous enclosures : non-darcian flow

The natural-convection flow and associated heat transfer in a fluid-saturated porous medium have been investigated using the generalized porous medium approach for a dome-shaped enclosure. Many new features have been predicted with the connective heat transfer and the shape of the top dome cover. The solutions are obtained for a wide range of Darcy and Rayleigh numbers for different offsets and eccentricities of the top dome covers. The detailed parametric study reveals that there is a significant change in heat transfer rate when the offset is between 0.2 and 0.4. Different shapes of conic section, such as circular, elliptical, parabolic, and hyperbolic are used for the top dome cover, and their effects on natural convection and heat transfer rates are studied.

A non-darcian numerical modeling in domed enclosures filled with heat-generating porous media

Numerical study of the natural-convection flow and heat transfer in a dome-shaped, heat-generating, porous enclosure is considered. The general conic equation for the top dome is used to consider various conical top sections such as circular, elliptical, parabolic, and hyperbolic. The individual effect of fluid Rayleigh, Darcy, and heat-generating parameters on flow patterns and heat transfer rates are analyzed and presented. The predicted results show that the heat-generating parameter has the most significant contribution toward the growth of bicellular core flow. Moreover, there is significant change in temperature distribution in comparison to rectangular enclosures, due to the existence of the domed-shape top adiabatic cover. The results also show that, regardless of Darcy and Rayleigh values, a flat adiabatic top cover tends to yield the highest value of Nusselt number, followed by circular, elliptical, parabolic, and hyperbolic top covers, respectively.

"Beyond number crunching" : applying qualitative techniques in sport marketing research

Valid and reliable research is pivotal to successful sport marketing strategy. Market research may be gathered via either quantitative or qualitative means. This paper explores the theoretical background and practical applications of qualitative research techniques. It explains the appropriate context for qualitative approaches, and discusses sampling procedures with particular emphasis on the powerful but simple technique known as theoretical sampling. In addition, it clarifies and explores data analysis procedures. The purpose of this paper is to provide sport market research practitioners with a model for implementing qualitative methodologies in sport marketing campaigns.

Number preference in Australian stocks

Stock price rallies/declines often terminate at price levels that are interpreted by many as areas of psychological resistance or support, while an alternative interpretation is that they coincide with price clusters. Some of these price levels tend to repeat with a regularity that is inconsistent with mere chance. In this paper, the existence of price clusters and psychological barriers is tested on a sample of 20 Australian stocks. We consider two number sequences, both derived from a base number of 100, as well as integer price levels. It is shown that Australian stock price data are not uniformly distributed and that for the majority of the stocks, price swing highs and lows are associated with certain recurring price levels. Some of the implications for trading and investing are considered.

Price exhaustion and number preference : time and price confluence in Australian stock prices

Confluence occurs when different trading filters generate signals that point to the same directional move. Using regression analysis, this paper investigates confluence trading signals associated with number preference and price exhaustion, for a sample of Australian stocks. The results show that certain price levels tend to act as psychological barriers, and that price exhaustion signals are a real phenomenon in the Australian stock market. It is shown also that confluence exists in the Australian stock market. Importantly, confluence is associated with price retracements that are of economic and statistical significance, offering profitable trading opportunities. The results suggest that Australian stocks do not follow a random walk.

Is more better? The relationship between outcomes achieved by problem gamblers and the number of counselling sessions attended

This paper addresses the question of how much intervention is necessary for the effective treatment of problem gambling by exploring the relationship between the number of counselling sessions attended and the degree of problem resolution achieved for 613 individuals who attended problem gambling counselling services in Victoria. While those who achieved partial or full resolution of presenting problems attended more sessions than those who finished counselling with their problems still unresolved, problems were typically reported as being resolved in fewer than five sessions. It is concluded that for some problem gamblers a relatively brief intervention may be sufficient.

Teachers' pre-conceptions of young children's conceptions of number

This paper uses data from several sources to argue that while teachers of young children are reasonably accurate in their predictions of when the majority of children will achieve mastery of specific objectives in mathematics, they are much less likely 10 be aware of the conceptions of high achieving children, and that, as a result, their classroom activities constrain these students' learning.

Montessori place-value and number expander cards

Montessori Cards are shown in the recently reprinted classic curriculum handbook (yellowcovered) 'Guidelines in Number' (1985, p 18). Unfortunately, exactly what this small, and limited sketch-picture might mean, in practice, is not necessarily clear. The use of Montessori number cards is discussed.