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The Tatun geothermal system, located in northern Taiwan, is hosted by the Plio-Pleistocene Tatun volcanic group, consisting dominantly of andesitic lavas, domes and pyroclastic flows. During the late 1960s and early 1970s, geologic mapping, geochemical sampling, geophysical surveys, and the drilling of numerous exploration and temperature gradient wells were conducted at Tatun under the leadership of the Mineral Research and Service Organization (MRSO), the predecessor to the geothermal group at the Industrial Technology Research Institute (ITRI). Deep (1–2 km) wells encountered commercial temperatures (200–300 °C) in the Matsao area, but these initial exploration efforts were discouraged by the presence of very acidic (pH < 3.5) and highly corrosive fluids. Numerous geoscience studies conducted over the past 15 years at Tatun have shown that the central portion of the system is dominated by corrosive volcanic fluids, as evidenced by abundant SO2 as well as HCl. More reduced gases are encountered on the flanks of the system, suggesting that water-rock interaction may have at least partly neutralized the volcanic-derived fluids on the margins of this geothermal system.

Seven accelerator mass spectrometry radiocarbon (AMS 14C) dates (7260±106∼7607±95 BP averaged 7444±103 BP) on a giant oyster shell, collected from an ancient shore of the Taipei Basin, are similar to the LSC (liquid scintillation counting) 14C age (7260±46 BP) of a grass sample inside the shell. The calibrated 14C ages of the C. gigas by Marine20 are 7490±240∼7805±230 cal BP (average 7660±96 cal BP), generally agreed with the calibrated LSC 14C ages of the grass and the oyster shell. Combined with other 14C ages of shoreline samples in the Taipei Basin, it is evident that sea level rose from 8600 to 7600 cal BP and reached a stand higher than modern sea level. During this marine transgression, the sedimentation rate along the shoreline was very high because 14C dating was not able to detect age differences for 4–5 m thick sediment sequences. Sixty-nine analyses of δ18O and δ13C from the oldest part of the shell exhibit clear seasonal cycles, with a 4-year period of growth in the 5.5-cm section. According to the δ18O values, the ancient oyster grew in a warmer-than-present shoreline environment, suggesting that the current absence of the giant oyster in Taiwan is not due to warming conditions. [ABSTRACT FROM AUTHOR]

The band-rejected designs of the printed open slot antenna for wireless local area network (WLAN)/worldwide interoperability for microwave access (WiMAX) applications are investigated. First, the broadband characteristic (2.3 ~ 6 [up arrow] GHz) of open slot antenna design with small size is implemented and measured. Then, inserted a single strip on the broadband antenna is studied and investigated. By inserting a strip on the printed open slot of the broadband antenna, to reject frequency from 3.56 to 4.58 GHz, a dual-broadband design of the open slot antenna with small size is obtained for WLAN applications in the 2.4 GHz (2400-2484 MHz) and 5 GHz (5150-5825 MHz) bands. Furthermore, by inserting two strips of different length on the open slot antenna, a three-band antenna is achieved. By adjusting the dimension of two strips on open slot antenna, a three operating modal frequencies at 2.37 ~ 2.72, 3.31 ~ 3.78, and 4.5 ~ 5.97 GHz for WiMAX application have been obtained. Detailed design steps and experimental results for the designs are studied and investigated in this paper. Index Terms--Band-rejected (band-notched) design/function, printed slot antenna, wireless local area network (WLAN), worldwide interoperability for Microwave Access (WiMAX).

The September 21, 1999, [M.sub.w] 7.6 Chichi earthquake destroyed several thousand buildings and caused more than 2000 fatalities in central Taiwan. The earthquake occurred along the Chelungpu fault, a thrust fault on the western flank of the Taiwan fold-and-thrust belt. The surface rupture was more than 90 km long, and vertical displacements ranged from 3 to 8 m. Although pre-existing scarps were identified along the Chelungpu fault, the fault had previously been categorized as a less important active fault, owing to the lack of geochronologic evidence and the failure to recognize fault-related geomorphic features. Identifying geomorphic features at active faults in Taiwan will permit the delineation of future surface ruptures and the determination of past magnitudes of past earthquakes, thus contributing to hazard assessment. Keywords: earthquake, rapture, faults, fault scarps, terraces.

A new design of a microstrip-line-fed circularly polarized printed ring slot antenna is proposed. Circular polarization (CP) radiation of the proposed design is achieved by introducing proper asymmetry in the ring slot structure and feeding the ring slot using a microstrip line at 45 [degrees] from the introduced asymmetry. The asymmetry introduced in the proposed design is a meandered-slot section and the proposed CP design can be applied to printed square and annular ring slot antennas. Prototypes of the proposed design have been implemented. Experimental results show that good CP radiation performances are obtained and the 3 dB axial-ratio CP bandwidths obtained for the square and annular ring slot antennas are about 4.3% and 3.5%, respectively. Index Terms--Circular polarization (CP), printed-ring-slot antenna.