Subsurface drainage technology may offer a useful option in improving crop productivity by preventing water-logging in poor drainage paddy fields. The present study compared two paddy fields with and without sheet-pipe type subsurface drainage on land and water productivities in Indonesia. Sheet-pipe typed is perforated plastic sheets with a hole diameter of 2 mm and made from high-density polyethylene. It is commonly installed 30–50 cm below the soil surface and placed horizontally by a machine called a mole drainer, and then the sheets will automatically be a capillary pipe. Two fields were prepared, i.e., the sheet-pipe typed field (SP field) and the non-sheet-pipe typed field (NSP field) with three rice varieties (Situ Bagendit, Inpari 6 Jete, and Inpari 43 Agritan). In both fields, weather parameters and water depth were measured by the automatic weather stations, soil moisture sensors and water level sensors. During one season, the SP field drained approximately 45% more water compared to the NSP field. Thus, it caused increasing in soil aeration and producing a more significant grain yield, particularly for Inpari 43 Agritan. The SP field produced a 5.77 ton/ha grain yield, while the NSP field was 5.09 ton/ha. By producing more grain yield, the SP field was more effective in water use as represented by higher water productivity by 20%. The results indicated that the sheet-pipe type system developed better soil aeration that provides better soil conditions for rice.

In this study, normally consolidated clays were subjected to undrained cyclic simple shear followed by drainage. Then the shear strain amplitudes (g) and number of cycles (n) were changed and the effects of Atterberg’s limits on the pore water pressure accumulation and recompression were investigated. In conclusion, the pore water pressure accumulation and the settlement of saturated clays are significantly affected by the Atterberg’s limits. For Kaolin with low plasticity index (I_p), the pore water pressure rapidly increases and becomes stable after relatively small number of cycles n. Meanwhile for Tokyo Bay clay and Kitakyushu clay with higher I_p, the cyclic shear-induced pore water pressure is rather small leading to smaller post-cyclic settlement. The cyclic recompression index (C_dyn) of Kaolin is unchanged with n while those of Tokyo Bay clay and Kitakyushu clay significantly decrease with n. By using these results, the post-cyclic settlement of clays was sucessfully predicted.

A textural surface pattern is used to add a physical or decorative function to an object's surface. We have proposed a milling technique involving patch division that can quickly generate a geometric surface pattern using a common profile-forming method. This report describes a method of generating a tool path using 3D-CAD and an FEA preprocessor applied to the patch division milling of a curved surface. Experimental results of the proposed method as applied to spherical and free-form surfaces are described.

For the sustainable restoration of wet farm land degraded by the climate change-induced rise of ground water level (GWL) and soil salinity etc., the sheet pipe system is one of the most useful technologies which reduces cultivation obstacles due to the poor drainage by controlling the rapid drainage function and enabling farmers to produce profitable crops. This system is characterized mainly as a perforated polyethylene rolled-band sheet 180 mm in width and 1 mm thick which is drawn into the subsurface layer while transforming a drainage pipe with φ = 50 mm. The major advantage of this system is that since the sheet pipe is installed without trenching, the disturbance of land is minimized and the construction period can be shortened to about 1/4 (which reduces the cost approximately by 50%). In this study, by using the sheet pipe installed miniature-type model soil box, the drainage capacity of the sheet pipe was confirmed as being the same as the pipe-shaped standard drainage pipes. Based on the observations of the saturated–unsaturated flow and the maximum lowering rate of GWL was predicted. Finally, at the farm land wherein the free board of the adjoining canal was limited, the effectiveness of the sheet-pipe system was confirmed.