Browsing by Author "Hung, WC"

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Estimating coefficients of volume compressibility from compression of strata and piezometric changes in a multiaquifer system in west Taiwan
(2004-09-01)
Liu, CH
;
Pan, YW
;
Liao, JJ
;
Hung, WC
;
土木工程學系
This paper estimates the coefficients of volume compressibility from variation in compressible! layer thickness and changes in piezometric heads by using detail ground surface surveys and a multilayer monitoring well at a selected site (Shigang) within the Choshui River alluvial fan in west Taiwan. The paper integrates various types of in situ monitoring tools, including leveling surveys, continuous global position system (GPS) stations, multilevel layer compression and groundwater pressure head-monitoring wells, to investigate the situation and progress of the subsidence problem in the region. The results from the cross-analyses of the measured data show that surface settlement caused by the compression of strata is between the depths of 60 and 210 m where the clayey stratum within 120-180 m was most pronounced and contributes up to 53% of the total compression. The results indicate that the clayey stratum is under normal consolidation. The results also reflect the fact that 20% of settlement contribution comes from the sandy stratum within 90-120 m; the elasto-plastic behavior of this sandy stratum is clear. The coefficients of volume compressibility of the clayey and sandy stratum analysed from the stratum's compression records; they were 6.38 x 10(-8) and 5.71 x 10(-9) m(2)/N, respectively. Ultimately, this parameter estimation would permit to control and predict land subsidence based on change in pressure head which are related to groundwater extraction. (C) 2004 Elsevier B.V. All rights reserved.
Photoionization spectra and ionization thresholds of CH3SO, CH3SOH, and CH3SS(O)CH3
(1996-11-01)
Hung, WC
;
Shen, MY
;
Lee, YP
;
Wang, NS
;
Cheng, BM
Photoionization efficiency (PIE) spectra of CH3SO, CH3SOH, and CH3SS(O)CH3 were measured in the spectral range 110-150 nm by means of a discharge flow system coupled to a photoionization mass spectrometer that employs a synchrotron radiation source, These species were generated bq reacting O atoms with CH3SSCH3 in the flow tube; a microwave discharge was employed to produce O atoms from O-2, Alternatively, C2H5SCH3 replaced CH3SSCH3 to form CH3SO, CH3SOH, and other products. Ionization thresholds of 8.99+/-0.02, 8.67+/-0.03, and 8.82+/-0.05 eV were determined for the first time for CH3SO, CH3SOH, and CH3SS(O)CH3, respectively, The former two values agree well with theoretical calculations with the G2 method, The latter value fits satisfactorily with those predicted for CH3SS(O)CH3 with the G2MP2 method; the G2 method was not employed in this case due to the numerous atoms in this molecule. Ionization thresholds of CH3S and CH3S2 were also determined to be 9.27+/-0.03 and 8.62+/-0.05 eV, respectively. experimental reports. (C) 1996 American Institute of Physics.