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Small-scale biomass CHP (combined heat and power) plants are in demand for environmental reasons -particularly systems fueled by wood waste, which are simple to operate and require no maintenance while having high thermal efficiency similar to oil-fired units. A 55kWe Stirling engine CHP system, combined with a simplified biomass combustion process that uses pulverized wood powder has been developed to meet these requirements. Wood powder of less than 500 µm was mainly used in these tests, and a combustion chamber length of 3 m was applied. Under these conditions, the air ratio can be reduced to 1.1 without increasing CO emissions by less than 10 ppm, and with combustion efficiency of 99.9%. Under the same conditions, NOx emissions are estimated to be less than 120 ppm (on the basis of 6% O 2 ). Wood powder was confirmed to have excellent properties as a fuel for Stirling engines. The 55 kWe Stirling engine performance test was carried out to optimize the operating condition of wood powder burners. The status of Stirling engine operation at a full load with 55 kWe was stable, and start-up and shut -down operations were easy to perform. Operational status was evaluated as being excellent, except for an ash fouling problem in the Stirling engine heater tubes. Ash fouling characteristics were considered in the final stage of the demonstration test. This paper summarizes the wood powder combustion test and Stirling engine performance test. Furthermore, the ash fouling data is shown and the mechanism of ash fouling in heater tubes is discussed.

In this paper, the construction period of the cruciform terraces with columns and the elevated causeways in the Angkor monuments of Cambodia is reconsidered, based on the results of our investigation of magnetic susceptibility and other characteristics of sandstone blocks. From an art-historical point of view, they are generally considered as modifications in the post-Bayon style period-the period during the reign of Jayavarman VIII (1243-95 CE) or later. However, from a lithological point of view, the average magnetic susceptibilities of the sandstone blocks in the cruciform terraces with columns and the elevated causeways are consistent with the rest of the monument. In addition, the characteristics of the sandstone blocks in the cruciform terraces, such as their shape, the orientation of the bedding plane and the stacking method, suggest that they were constructed in the same period as the rest of the monument.

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