Seismic analysis of long multiple-span highway bridges     

W. S. Tseng  J. Penzien 《地震工程与结构动力学》1975,4(1):1-24

Mathematical models and three-dimensional non-linear dynamic analysis procedures are described for determining the seismic response of long, curved (or straight), multiple-span, reinforced concrete highway bridges. Under the action of strong earthquakes, the columns (or piers) of such structures may experience large cyclic inelastic deformations of a coupled form. Also, cyclic slippage of the Coulomb type can take place in the expansion joints of the deck causing multiple impacts and separations to occur. These separations may be sufficiently large to cause tensile yielding of the longitudinal expansion joint restrainer bars (or cables) and, if not controlled, can permit deck spans to fall off their supports resulting in partial or total collapse of the structure. In this paper, a three-dimensional elasto-plastic mathematical model suitable for representing the coupled inelastic flexural behaviour of reinforced concrete columns under cyclic deformations is presented along with a non-linear mathematical model for simulating the non-linear discontinuous behaviour of expansion joints. The procedures used for non-linear seismic response analysis are described and a numerical example is given to illustrate the method.  相似文献   

Anomalous hydrographic and biological conditions in the northern South China Sea during the 1997–1998 El Niño and comparisons with the equatorial Pacific     

Chun-Mao Tseng  K.-K. Liu  L.-W. Wang  G.-C. Gong 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(12):2129-2143

It is demonstrated that weakened wind mixing and strengthened water column stratification resulted in the anomalously low sea surface chlorophyll in the northern South China Sea during the 1997–1998 El Niño event. Remotely sensed sea surface temperature, wind and chlorophyll, which were validated by shipboard observations at the SouthEast Asian Time-series Study (SEATS) station (18°N, 116°E) in the northern South China Sea (SCS) provided the basis for this study. During the 1997–1998 winter at the SEATS station, the sea surface temperature was elevated by about 2 °C above the climatological mean, while the wind speed of the northeast monsoon was reduced from a climatological mean of 9.4 to 6.8 m/s. The concentration of surface chlorophyll-a dropped from 0.2 to 0.1 mg/m³. The monthly area-averaged integrated primary production estimated for the northern SCS area (112–119°E, 15–21°N) was reduced by about 40% of the normal winter value. Under the anomalously high sea surface temperature and weak monsoon, the mixed-layer depth would have been reduced from an average of 65 to 45 m and the nutrients in the mixed layer would have been reduced by half, according to observations at the SEATS station in more recent years. During the 1997–1998 El Niño event, the onset of warming in the northern SCS lagged behind that in the eastern equatorial Pacific by about 5 months and lingered for 11 months. This course of change resembled that of the western Pacific warm pool region. However, contrary to the northern SCS, the sea surface chlorophyll was enhanced in the warm pool region during the event, probably mainly because of the uplifted nutricline. Unlike the eastern equatorial Pacific, the dramatic recovery of biological production did not happen in the SCS in the summer of 1998. These distinctive biogeochemical responses reflect fundamental differences between the SCS and the equatorial Pacific in terms of upper water column dynamics.  相似文献   

Improving debris flow monitoring in Taiwan by using high-resolution rainfall products from QPESUMS   总被引：2，自引：2，他引：2  

Chien-Yuan Chen  Lee-Yao Lin  Fan-Chieh Yu  Ching-Sheng Lee  Chun-Chieh Tseng  An-Hsiang Wang  Kei-Wai Cheung 《Natural Hazards》2007,40(2):447-461

Debris flow is commonly initiated by torrential rain and its triggering is correlated to the hydrological, geological, and geomorphic conditions on site. In spite of the important effects of geology and topography, rainfall characteristic is the main external triggering factor to debris flow and is a predominant parameter for real-time monitoring. Due to the scarcity of sufficient spatial ground-based rainfall data in hill areas, quantitative precipitation estimation using remote-sensing techniques such as radar and satellite is needed for debris flow pre-warning. The QPESUMS (Quantitative Precipitation Estimation and Segregation Using Multiple Sensors) system was acquired to retrieve spatial rainfall data during the rainfall period from June 30 to July 6 in 2004 when Typhoon Mindulle and southwesterly flow struck Taiwan. The retrieved data were used for setting up the debris flow monitoring algorithm. With the aid of multiple platforms of meteorological observations, a rainfall threshold isohyet in a pilot area was mapped for debris flow monitoring. The rainfall monitoring algorithm based on QPESUMS provides more detailed information than the limited number of ground-based rainfall stations for interpreting the spatial distributions of rainfall events, and therefore is more suitable for debris-flow monitoring.  相似文献   

The carbonate system in the East China Sea in winter     

Wen-Chen Chou  Gwo-Ching Gong  Chun-Mao Tseng  David D. Sheu  Chin-Chang Hung  Lo-Ping Chang  Li-Wen Wang 《Marine Chemistry》2011,123(1-4):44-55

Measurements of dissolved inorganic carbon (DIC), pH, total alkalinity (TA), and partial pressure of CO₂ (pCO₂) were conducted at a total of 25 stations along four cross shelf transects in the East China Sea (ECS) in January 2008. Results showed that their distributions in the surface water corresponded well to the general circulation pattern in the ECS. Low DIC and pCO₂ and high pH were found in the warm and saline Kuroshio Current water flowing northeastward along the shelf break, whereas high DIC and pCO₂ and low pH were mainly observed in the cold and less saline China Coastal Current water flowing southward along the coast of Mainland China. Difference between surface water and atmospheric pCO₂ (ΔpCO₂), ranging from ~ 0 to ? 111 μatm, indicated that the entire ECS shelf acted as a CO₂ sink during winter with an average flux of CO₂ of ?13.7 ± 5.7 (mmol C m^? 2 day^? 1), and is consistent with previous studies. However, pCO₂ was negatively correlated with temperature for surface waters lower than 20 °C, in contrast to the positive correlation found in the 1990s. Moreover, the wintertime ΔpCO₂ in the inner shelf near the Changjiang River estuary has appreciably decreased since the early 1990s, suggesting a decline of CO₂ sequestration capacity in this region. However, the actual causes for the observed relationship between these decadal changes and the increased eutrophication over recent decades are worth further study.  相似文献   

Assessment of Cryosat-2 and SARAL/AltiKa altimetry for measuring inland water and coastal sea level variations: A case study on Tibetan Plateau lake and Taiwan Coast     

Huan-Chin Kao  Kuo-Hsin Tseng  C.K. Shum  Tzu-Pang Tseng  Yuan-Yuan Jia 《Marine Geodesy》2019,42(4):327-343

Satellite altimetry has been proven as an effective technology to accurately measure water level, ice elevation, and flat land surface changes since the 1990s. To overcome limitations of pulse-limited altimetry, new altimetric missions such as Cryosat-2 and Satellite with ARgos and AltiKa (SARAL/AltiKa), have been designed to have higher along-track spatial resolution to measure more accurately inland water levels for small water bodies, and coastal sea level changes. In this study, we evaluate the performance of Cryosat-2 low-resolution (LRM) and SARin modes and SARAL/AltiKa Ka-band data on two connected lakes in central Tibetan Plateau, and in the coastal region of Taiwan. Results are compared with in situ tide gauge data in Taiwan and altimetric lake level time series from the CNES Hydroweb database. Our results show that water level change trends observed by Cryosat-2 20-Hz retracked observations, the SARAL/AltiKa 40-Hz Ice-1 retracked data, and the Hydroweb measurements are consistent with the estimated water level trend of ～0.30?m/y, during 2011–2017, and 2013–2015, for the Tibetan Migriggyangzham Co and Dorsoidong Co, respectively. For the coastal region, the performance of SARAL/AltiKa is better than that of Cryosat-2 LRM data in Taiwan. This finding demonstrates the superiority of the Ka-band over Ku-band radar altimetry.  相似文献   

Super-ensemble of three RCMs for climate projection over East Asia and Taiwan     

Chung-Ming Liu  Ming-Chin Wu  Sahana Paul  Ying-Chen Chen  Shu-Hua Lin  Wei-Shiang Lin  Yen-Chih Lee  Huang-Hsung Hsu  Ren-Yow Tseng  Cheng-Ta Chen 《Theoretical and Applied Climatology》2011,103(1-2):265-278

Runs of three regional climate models (RCMs) dynamically downscaling the outputs of atmosphere?Cocean coupling general circulation models (AOGCMs) are studied. These RCMs are NCAR-MM5, NCEP-RSM (Regional Spectral Model), and Purdue-PRM (Purdue Regional Model). A useful approach is developed to compare the variability, error, and spatial distribution of model-simulated results with respect to the Climatic Research Unit (CRU) datasets over East Asia and seven sub-regions during the 1990s. The results show that NCEP-RSM outperforms the other two in meeting criteria selected on evaluating the model performance. Furthermore, three super-ensemble approaches are tested on merging RCMs?? outputs. The inverse of the square error summation (ISES) method is selected as a suitable method with a generally good performance during the verification period. The projected future climate changes by ISES indicate larger temperature increases over high-latitude continent and smaller over low-latitude maritime areas. Rainfall will increase in summer over the central simulation domain, i.e. the eastern China, but decrease in winter, which are clearly linked to the variation in the synoptic airflows. Also, a more frequent occurrence of extreme rainfall events than what happened in the 1990s is projected. The projection over Taiwan suggests strong warming in summer, followed by autumn, winter, and spring. The interaction between the synoptic flow and the local terrain affects significantly the changes in precipitation. In general, larger change of the variability of rainfall will be over areas with lesser rainfall in the future, while lesser change will be over areas with more projected rainfall.  相似文献   

Studies on the Dasycladales (Chlorophyta) of China     

Dong Meiling  C. K. Tseng 《中国海洋湖沼学报》1985,3(1):1-22

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Seasonal and interannual variability of carbon cycle in South China Sea: A three-dimensional physical-biogeochemical modeling study   总被引：5，自引：1，他引：4  

Fei Chai  Guimei Liu  Huijie Xue  Lei Shi  Yi Chao  Chun-Mao Tseng  Wen-Chen Chou  Kon-Kee Liu 《Journal of Oceanography》2009,65(5):703-720

The South China Sea (SCS) exhibits strong variations on seasonal to interannual time scale, and the changing Southeast Asian Monsoon has direct impacts on the nutrients and phytoplankton dynamics, as well as the carbon cycle. A Pacific basin-wide physical-biogeochemical model has been developed and used to investigate the physical variations, ecosystem responses, and carbon cycle consequences. The Pacific basin-wide circulation model, based on the Regional Ocean Model Systems (ROMS) with a 50-km spatial resolution, is driven with daily air-sea fluxes derived from the National Centers for Environmental Prediction (NCEP) reanalysis between 1990 and 2004. The biogeochemical processes are simulated with the Carbon, Si(OH)₄, Nitrogen Ecosystem (CoSINE) model consisting of multiple nutrients and plankton functional groups and detailed carbon cycle dynamics. The ROMS-CoSINE model is capable of reproducing many observed features and their variability over the same period at the SouthEast Asian Time-series Study (SEATS) station in the SCS. The integrated air-sea CO₂ flux over the entire SCS reveals a strong seasonal cycle, serving as a source of CO₂ to the atmosphere in spring, summer and autumn, but acting as a sink of CO₂ for the atmosphere in winter. The annual mean sea-to-air CO₂ flux averaged over the entire SCS is +0.33 moles CO₂ m⁻²year⁻¹, which indicates that the SCS is a weak source of CO₂ to the atmosphere. Temperature has a stronger influence on the seasonal variation of pCO₂ than biological activity, and is thus the dominant factor controlling the oceanic pCO₂ in the SCS. The water temperature, seasonal upwelling and Kuroshio intrusion determine the pCO₂ differences at coast of Vietnam and the northwestern region of the Luzon Island. The inverse relationship between the interannual variability of Chl-a in summer near the coast of Vietnam and NINO₃ SST (Sea Surface Temperature) index in January implies that the carbon cycle and primary productivity in the SCS is teleconnected to the Pacific-East Asian large-scale climatic variability.  相似文献   

Comparison of high-energy galactic and atmospheric tau neutrino flux     

H. Athar  Kingman Cheung  Guey-Lin Lin  Jie-Jun Tseng   《Astroparticle Physics》2003,18(6):581-592

We compare the tau neutrino flux arising from the galaxy and the earth atmosphere for 10³E/GeV10¹¹. The intrinsic and oscillated tau neutrino fluxes from both sources are calculated. The intrinsic galactic ν_τ flux (E10³ GeV) is calculated by considering the interactions of high-energy cosmic-rays with the matter present in our galaxy, whereas the oscillated galactic ν_τ flux is coming from the oscillation of the galactic ν_μ flux. For the intrinsic atmospheric ν_τ flux, we extend the validity of a previous calculation from E10⁶ GeV up to E10¹¹ GeV. The oscillated atmospheric ν_τ flux is, on the other hand, rather suppressed. We find that, for 10³E/GeV5×10⁷, the oscillated ν_τ flux along the galactic plane dominates over the maximal intrinsic atmospheric ν_τ flux, i.e., the flux along the horizontal direction. We also briefly mention the presently envisaged prospects for observing these high-energy tau neutrinos.  相似文献   

Default risk-based probabilistic decision model for risk management and control   总被引：5，自引：5，他引：0  

Cheng-Wu Chen  Chun-Pin Tseng 《Natural Hazards》2012,63(2):659-671

This study describes how risk-based risk control allocation models work. We begin by discussing the economic rationale for allocating risk control in a diversified organization such as an enterprise. For a probability model for risk control decision making under uncertainty and risk, we propose a model involving stochastic total loss amount constraints with respect to various tolerable default levels. Our main objective is to develop a method that will allow shaping of the risk associated with risk control outcomes. The direct and indirect losses caused by simulated disasters can be estimated using an engineering and financial analysis model. Based on this model, we can generate an exceeding probability curve and then calculate how much of the loss can be eliminated or transferred to other entities should funds be allocated to risk control. The optimal natural disaster risk control arrangement with a probabilistic formulation is explained in this paper. Results from the proposed formulations are compared in case studies. The model attempts to apply risk-based budget guidelines to risk reduction measurement within a portfolio-based risk framework.  相似文献