This study explores the limits of cooling for handheld devices based on both testing and simulation under various conditions and provides guidelines for maximizing the amount of power that can be dissipated in these small form-factor devices. The factors affecting the maximum possible power dissipation are the available surface area and surface finishes, selection of the outer shell materials, thermal interface materials, heat spreaders and air gaps. In most cases, the limiting factor in the thermal design of these devices is not the temperatures of the internal components but the temperature of the external surfaces since these are in direct contact with the skin of the user. There have been studies that address the maximum allowable comfortable touch temperature of a handheld device. This study presents methods for maximizing the internal power dissipation of these devices while limiting the touch temperatures to the maximum comfortable limits.

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Handheld devices are increasingly capable of running applications that used to require laptop and desktop computers. The requirement that these devices provide better performance with a smaller form factor or size presents significant challenges, especially with the limitations of passive cooling. The current study presents a summary of the cooling solutions of several popular, commercially available tablets. The trends in power dissipation and thermal management techniques of handheld devices are presented. The factors affecting the maximum possible power dissipation are discussed. The effects of the selection of the outer shell materials, the thermal interface materials, heat spreaders and air gaps are presented. For all considered thermal management techniques of handheld devices, a figure of merit for the cooling solutions is defined as: Figure of Merit = Maximum Power Dissipation / Surface Temperature Rise, in (W/degC). This figure of merit allows for an objective comparison of the available cooling solutions.

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Near Kinyra, at the eastern coast of Thasos several ancient galleries were found during the 1979 field- season. The galleries extend up to 100 m into the ridge of Klisidi. They contain numerous traces of ancient mining activity. Mineralogical and chemical studies on limonitic ore samples reveal that gold is the only metal in these galleries which was worth mining in antiquity. The galleries very likely belong to the ancient gold mines which Herodotus described in this area and which, so far, had not been re-located.