Experimental ablation processes study on an electrothermal launcher
An experimental parametric study has been performed to analyse the influence of time on the ablation processes in the capillary of an electrothermal launcher. A 600 kJ, 16 cells pulse forming network (PFN) was used. The time discharge was varied from 350 /spl mu/s to 100 /spl mu/s by changing the cell number (from 16 to 4) and then the capacitance (from 1760 /spl mu/F to 440 /spl mu/F). The parametric study has been performed at a constant voltage level (13 kV). The ablated masses have been measured for different time discharge and the results have been compared with a 0-D code.
A global theoretical approach for the electrothermal gun: scaling laws and a 0-D time-dependent model
In this paper, a theoretical analysis of the physical processes taking place in the electrothermal gun is presented. In a first step, using the basic conservation equations (energy, mass, charge) integrated over the whole time of the discharge, scaling laws are derived. These laws provide the temperature, the mass, the resistance of the plasma and the current going through it, as functions of the stored electrical energy. In a second step, a 0D time-dependent model is presented. This model takes into account the evolution of the complete system consisting of the electrical source, the plasma burner and the motion of the projectile. Special attention is given to the ablation phenomena and a microscopic description which differs from prior publications is derived. Finally, comparisons with experiments are given and good agreements are obtained. >
Gambling and Problem Gambling in Sweden: Changes Between 1998 and 2009
Gambling participation and rates of problem gambling change over time in response to a variety of factors including gambling availability, demographic changes and adaptation at individual and societal levels. These relationship are complex and only partially understood. The major aim of the present study was to provide general population estimates of gambling participation and problem gambling for Sweden and compare these estimates with estimates from a previous national study. The study was also designed to identify risk factors for problem gambling including change in these factors over time. Data are from the first phase of the Swedish Longitudinal Gambling Study (Swelogs) in which a representative sample of 8,165 people was assessed using validated problem gambling and other measures to facilitate comparison with findings from the 1997/1998 Swedish Gambling Study (Swegs). Overall, it was found that gambling participation reduced markedly, although in some population sectors increases were evident for some forms including poker and electronic gaming machines. Lifetime prevalence of probable pathological gambling increased; however, past 12 months probable pathological and problem gambling prevalence did not. Males, younger adults and people born outside Sweden were at high risk in both studies. Significant prevalence increases were evident for people aged 18–24 and those with low levels of education. The results indicate that relationships between gambling exposure, participation and problems are dynamic with shifting implications for public health and social policy.