Taiwan High Speed Rail (THSR), which began operations in January 2007, passes through an area in Yunlin County where the largest cumulative subsidence measured during 1992-2006 exceeds 100 cm. Leveling benchmarks, GPS pillars and multilevel monitoring wells were deployed in this area to collect detailed subsidence data from October 2003 to 2006. Leveling is carried out on both ground benchmarks and survey bolts attached to THSR columns. Minimum constraint solutions of leveling networks produce estimated heights accurate to a few mm. Special attention is paid to code smoothing, ionospheric, tropospheric and ocean tidal loading (OTL) effects, so that height estimates from GPS are optimal. Leveling and GPS-derived height changes are consistent to 1 cm, and show that from Stations 210 to 240K of TSHR, the subsidence is bowl shaped. Measurements of sediment compaction in specific depth intervals at three monitoring wells indicate that most of the subsidence is caused by sediment compaction at depths from 50 to 300 m. The major compaction occurs in the interval 220-300 m and is attributed to ground water withdrawal. Large angular deflections as determined from subsidence measurements are detected at some columns, but are below the upper bound (1/1,000) of tolerance specified in the safety code. With the current subsidence and sediment compaction, no significantly reduced loading capacity of the columns is expected to occur. For a safe THSR operation, subsidence and sediment-compaction monitoring should be continued, and current ground water withdrawal in Yunlin must be reduced or stopped.

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An organic Rankine cycle system comprised of a preheater, evaporator, condenser, turbine, generator, and pump was used to study its off-design performance and the operational control strategy. R245fa was used as the working fluid. Under the design conditions, the net power output is 243 kW and the system thermal efficiency is 9.5%. For an off-design heat source flow rate (m W ), the operating pressure was controlled to meet the condition that the R245fa reached the liquid and vapor saturation states at the outlet of the preheater and the evaporator, respectively. The analytical results demonstrated that the operating pressure increased with increasing m W ; a higher m W yielded better heat transfer performance of the preheater and required a smaller evaporator heat capacity, and the net power output and system thermal efficiency increased with increasing m W . For the range of m W studied here, the net power output increased by 64.0% while the total heat transfer rate increased by only 9.2%. In summary, off-design operation of the system was examined for a heat source flow rate which varied by -39.0% to +78.0% from the designed rate, resulting in -29.2% to +16.0% and -25.3% to +12.6% variations in the net power output and system thermal efficiency, respectively. OPEN ACCESSEnergies 2014, 7 3685

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