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We are in the process of developing a doppler borehole televiewer (DBHTV) which quantitatively evaluates the permeability of independent subsurface fractures in a borehole. The system employs an ultrasonic pulsed Doppler method, and is compatible with the conventional acoustic borehole imaging system called borehole televiewer (BHTV). Using the DBHTV, back-scattered waves from fine particles in the borehole fluid such as drill mud or cuttings in a water filled borehole are detected along with the reflected waves from the borehole wall, and the Doppler shift of the back-scattered waves is used to estimate the fluid velocity. A method to estimate the distribution of Doppler shift was examined using a laboratory experimental model. An attempt to locate the sampling volume and a method to quantitatively estimate the flow velocity by scanning the transducer are examined. This study shows that the location of permeable fractures, the distribution of fluid velocity and the fluid volume can be visualized using the DBHTV.

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Using a cell module with a porous carbon plate, two‐way operations of a specific direct methanol fuel cell (DMFC) with a vapor feed (VF) of neat methanol and a liquid feed (LF) of a dilute methanol solution were conducted, and the cell performances were compared to each other in order to clarify which condition produced the better performance. The comparison was conducted at different air humidities, i.e., 30, 60, 90 and 100%, and cell temperatures, i.e., 313, 323 and 333 K. As a result, about a 10% higher power density was obtained by the LF‐DMFC, whereas about a 2% higher efficiency was obtained by the VF‐DMFC at the optimum air humidity and 323 K. These performances were achieved by significantly different mass transports through the membrane.