Friction cost approach

Beside their calculation of direct costs, Stoll et al. (2002a) also examined indirect costs in a German sample of HIV-infected patients after the introduction of HAART. To emphasize the implications of different approaches of indirect costs, the authors determined both costs based on the human capital approach and costs calculated on the friction cost approach. They concluded that indirect costs based on the friction approach per patient in 1997 (US 2,421) add up to only one-tenth of the amount derived from the human capital approach (US 24,639). 

The friction cost method (Koopmanschap et al. 1995) assumes that the human capital approach has a tendency to overestimate the indirect household costs. If a worker is seriously sick or dies, his job will be vacant for some time until a new person is hired or trained. However, the loss will not be there for many years. Therefore, the loss of human capital is calculated not until the time of retirement, but until the time of replacement. This approach is correct for unskilled labor in a situation of unemployment. It fits neither to a fully employed economy nor to a subsistence farmer society where there is no substitution of a father who died. 

There is a growing body of literature on the costs of HIV/AIDS (Homberger et al. 2007), but all studies address only one branch of the COI tree (Fig. 1). Until now there is not a single publication fully covering all aspects of COI of HIV/AIDS, and different methodologies (such as human capital approach vs. friction cost method) make comparison difficult. In addition, the time lag between the year of the study and the publication is between 3 and 10 years. That is one reason why we know so little about the costs of the last 5 years results are not yet published. 

Traditionally mining headframes are constructed over the mine shaft to facilitate hoisting, provide head cover, facilitate safe access to the shaft and in some cases, to house a tower mounted friction hoist. In an effort to increase production and minimize down time, schedule, capital and construction costs, an approach was conceived to convert an existing service shaft into a production shaft. To better streamline the conversion process, a two phased approach was developed for the surface conversion. First, a penthouse would be constructed over the existing operational headframe and outfitted with a pre-commissioned hoisting plant. Second, the existing service headframe would be demoHshed and replaced with a new modular production headframe complex. 

Cost reduction activities by reducing treat rate and process improvements are continually occurring, as are formulating approaches to improved compatibility with low friction/fiiel economy systems, improved viscometrics and incorporation of EP/antiwear and low S/P/Cl and ashless components. 

More recently an entirely different approach has been proposed [121,122] in which particles couple to the fluid through a frictional drag. This method has the advantage of greatly reducing the number of LB grid points in the simulation, at the cost of a representation that is only correct in the far field. The method has been... 

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