An RBF‐based model with an information processor for forecasting hourly reservoir inflow during typhoons     

Gwo‐Fong Lin  Ming‐Chang Wu  Guo‐Rong Chen  Fei‐Yu Tsai 《水文研究》2009,23(25):3598-3609

Inflow forecasting is essential for decision making on reservoir operation during typhoons. In this paper, a radial basis function (RBF)‐based model with an information processor is proposed for more accurate forecasts of hourly reservoir inflow. Firstly, based on the multilayer perceptron neural (MLP) network, an information processor is developed to pre‐process the typhoon information (namely, typhoon characteristics and rainfall) and to produce forecasts of rainfall. The forecasted rainfall and the observed inflow are then used as input to the RBF‐based model, which is a nonlinear function approximator, to produce forecasts of hourly inflow. For parameter estimation of the RBF‐based model, the fully‐supervised learning algorithm is used. Actual applications of the proposed model are performed to yield 1‐ to 6‐h ahead forecasts of inflow. To assess the improvement due to the use of the typhoon information processor, models without the typhoon information processor are constructed and compared with the proposed model. The results show that the proposed model performs the best and is capable of providing improved forecasts of hourly inflow, especially for long lead‐time. In conclusion, the proposed model with a typhoon information processor can extract useful information from typhoon characteristics and rainfall, and consequently improve the forecasting performance. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Reduction of discharge hydrograph and flood stage resulted from upstream detention ponds     

Ching-Nuo Chen  Chih-Heng Tsai  Chang-Tai Tsai 《水文研究》2007,21(25):3492-3506

The models of physiographic inundation and flood routing for channel network were used in this study to analyse the influence of the Tainan Scientific Base Industrial Park (TSBIP) and Feng-Hua detention ponds on the inundated potential, inundated volume, flood damage, and flood stage of peak flow along the Yen-Shui creek in 2-day flood for the 2-, 10- and 50-year return periods, respectively. The computed results show that the TSBIP detention ponds are able to reduce the inundated area and flood damage. However, the decrease in inundated area is not obvious for the 50-year return-period flood. Construction of the Feng-Hua detention pond resulted in a significant decrease in the flood stage along the Yen-Shui creek in the downstream reach. Moreover, the decrease in peak flow and lag of time-to-peak become increasingly evident in the downstream direction for the 2- and 10-year return-period events. For the 50-year return period, the lag of time-to-peak is not apparent, but the decrease in peak flow is still noticeable. In respect to the performance of detention ponds, the slopes of hydrographs in the rising and recession segments are smoother than those without detention ponds. Meanwhile, the shapes of peak become flatter if the detention ponds are installed. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Acoustic wave scattering from a rough seabed over a sediment layer with generalized-exponential density and inverse-square sound speed profiles     

Jin-Yuan Liu  Sheng-Hsiung Tsai  I-Chun Lin 《Ocean Engineering》2004,31(3-4):417-434

This paper considers acoustic plane wave scattering from a rough seabed on a transition sediment layer overlying an elastic sea basement. The transition sediment layer is assumed to be fluid-like, with density and sound speed distributions behaving as generalized-exponential and inverse-square functions, respectively. This specific class of density and sound speed profiles deserves special attentions not only because it is geologically realistic, but also renders analytical solutions to the Helmholtz equation, making it particularly useful in the study of ocean and seabed acoustics. Based upon a boundary perturbation approach, the computational algorithm for the spatial spectrum in terms of the power spectral density of the scattered field has been developed and implemented. The results have shown that, while the coherent field mainly depends upon the gross structure of the seabed roughness, e.g., RMS roughness, the scattered field is significantly affected by the details of the roughness distributions specialized by the roughness power spectrum and the spatial correlation length of the rough surface. The dependence of the power spectral density of the scattered field on the various types of sediment stratifications, including the constant and the k²-linear sound speed distributions, is also included in the analysis.  相似文献   

GPS radio occultation measurements on ionospheric electron density from low Earth orbit   总被引：1，自引：0，他引：1  

L.-C. Tsai  Kai-Chien Cheng  C. H. Liu 《Journal of Geodesy》2011,85(12):941-948

Since the proof-of-concept GPS/Meteorology (GPS/MET) experiment successfully demonstrated active limb sounding of the Earth’s neutral atmosphere and ionosphere via GPS radio occultation (RO) from low Earth orbit, the developments of electron density (n _e) retrieval techniques and powerful processing systems have made a significant progress in recent years. In this study, the researches of n _e profiling from space-based GPS RO observations are briefly reviewed. Applying to the Formosat-3/Constellation Observing System for Meteorology, Ionosphere and Climate (FS3/COSMIC) data, we also present a compensatory Abel inversion technique including the effects of large-scale horizontal gradients and/or inhomogeneous ionospheric n _e obtained from an improved near real-time phenomenological model of the TaiWan Ionospheric Model. The results were evaluated by the ionosonde foF2 and foE data and showed improvements of rms foF2 difference from 29.2 to 16.5% in relative percentage and rms foE difference from 54.2 to 32.7% over the standard Abel inversion.  相似文献   

Performance‐based seismic assessment method for Taiwanese historic Dieh‐Dou timber structures     

Pin‐Hui Tsai  Dina D'Ayala 《地震工程与结构动力学》2011,40(7):709-729

Lateral force, response spectrum and step‐by‐step pushover analyses are performed and compared with the post‐earthquake survey of two Dieh‐Dou buildings seriously affected in the 1999 Chi‐Chi earthquake in Taiwan. The results show that the proposed FE model with finite translational and rotational stiffness can successfully be employed to assess the vulnerability of the frames. The fundamental period of Dieh‐Dou structures is about 1.0 s higher than that calculated by the simplified approach of the codes for regular frames; a modal analysis is, therefore, essential for this typology of structure. The elastic analysis, either lateral force or response spectrum, is shown to be reliable to assess Dieh‐Dou frames when quick results are desired. However, a non‐linear step‐by‐step pushover analysis has the advantage of greater accuracy, as it allows mapping the failure trend and indicating the critical elements. The lateral drifts are compared with the actual observed damage pattern and when the damage level is related to the peak ground acceleration on a vulnerability curve plot, it is shown that the joint failure combined with the lateral drift gives an indication of the global structural behaviour of this historic construction typology. Owing to the unique construction features of the Dieh‐Dou, the joint failure represents also a critical criterion in terms of maximum retention for conservation. Based on a damage level approach, an assessment methodology is suggested that would allow optimizing a strengthening strategy, for protection of these precious structures from future earthquakes while avoiding unnecessary interventions. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Estimation of the seismic energy demands of two-way asymmetric-plan building systems     

Jui-Liang Lin  Keh-Chyuan Tsai 《Bulletin of Earthquake Engineering》2011,9(2):603-621

This paper proposes a method for the estimation of the seismic energy demands of two-way asymmetric-plan buildings under bi-directional ground excitations. The modal absorbed energies of asymmetric-plan buildings are estimated by using the three-degree-of-freedom (3DOF) modal systems. The 3DOF modal system represents the two roof translations versus the two base shears and the roof rotation versus the base torque relationships of each vibration mode of two-way asymmetric-plan buildings. Not only the total absorbed energy but also the portions of the total absorbed energy contributed from translational and rotational deformations can be respectively estimated. This study verifies the relationship between the signs of modal eccentricities and the trend of uneven distribution of modal absorbed energy on floor-plan edges of asymmetric-plan buildings. The accuracy of the proposed method was verified by analyzing one 3-storey and one 20-storey two-way asymmetric-plan buildings subjected to bi-directional ground motions. The computational efficiency of the proposed method is confirmed by comparing the computation time with that required by using the nonlinear response history analysis.  相似文献   

Improving information access for emergency response in disasters     

Ming-Kuan Tsai  Nie-Jia Yau 《Natural Hazards》2013,66(2):343-354

During disasters, many researchers highlight the efficiency of the various information techniques that are used for emergency response. However, only a few information systems consider on-site and off-site information requirements synchronously. The results achieved by the emergency responders will not be as effective as they should be, since the emergency responders cannot access necessary information. Therefore, this study proposed an approach for dealing with three problems associated with emergency situations, i.e., inadequate escape guidelines for people, incomplete geographical information for relief workers, and insufficient on-site information for disaster managers. In a simulated scenario, when serious debris flows occurred, this study tested the approach. The test results showed that the people rapidly finished self-evacuation, the relief workers effectively completed their on-site relief work, and the disaster managers successfully managed the on-site activities regarding the people and relief workers. Overall, the recommended approach improved information access for emergency response and provided a useful reference for similar applications in disaster management.  相似文献   

Application of a feature-based approach to debris flow detection by numerical simulation     

Chih-Wei Lin  Cheng-Wu Chen  Wen-Ko Hsu  Chia-Yen Chen  Chung-Hung Tsai  Yi-Ping Hung  Wei-Ling Chiang 《Natural Hazards》2013,67(2):783-796

A debris flow is a serious natural disaster which can occur anywhere whether in a valley or on a mountain slope, destroying everything it passes through. Debris flows can occur suddenly and cause residents in the path to suffer casualties and property loss. An early warning system is necessary to reduce the damage in order to protect human life and personal property. However, most debris flow detection systems, like wireless sensors, satellite images and radar, are not suitable for general public use. Vision surveillance systems are generally erected in Taiwan as public devices for security. Therefore, we propose a novel debris early warning system that uses a computer vision technique and build a simulation environment to prove the feasibility.  相似文献   

Indicator geostatistics for reconstructing Baton Rouge aquifer-fault hydrostratigraphy, Louisiana, USA     

Ahmed S. Elshall  Frank T.-C. Tsai  Jeffrey S. Hanor 《Hydrogeology Journal》2013,21(8):1731-1747

The complex siliciclastic aquifer system underneath the Baton Rouge area, Louisiana (USA), is fluvial in origin and is characterized by strongly binary heterogeneity of sand units and mudstones as pervious and impervious hydrofacies. The east–west trending Baton Rouge fault and Denham Springs-Scotlandville fault cut across East Baton Rouge Parish and play an important role in groundwater flow and aquifer salinization. This study reconstructs the Baton Rouge aquifer-fault system architecture for a Miocene-Pliocene depth interval that consists of the 1,200-foot sand to the 2,000-foot sand. The results show the spatial extent of sand units, their interconnections, and flow paths within each sand unit. The regional-scale formation dip, the sand unit offset on the faults, and the volumetric spatial extent of individual sand units are quantified. The study reveals the complexity of the Baton Rouge aquifer-fault system where the sand deposition is non-uniform, different sand units are interconnected, the sand unit displacement on the faults is significant, and the spatial distribution of flow pathways through the faults is sporadic. The identified locations of flow pathways through the Baton Rouge fault provide useful information on possible windows for saltwater intrusion from the south.  相似文献   

Evaluating heavy metal concentration of plants on a serpentine site for phytoremediation applications   总被引：1，自引：0，他引：1  

Cheng-Ping Ho  Zeng-Yei Hseu  Nien-Chu Chen  Chen-Chi Tsai 《Environmental Earth Sciences》2013,70(1):191-199

The chemical analysis of plants and soils is a frequently used approach in understanding a serpentine ecosystem. Studies on vegetation growth in serpentine soils focused on various plant species for remediation purposes of soil contamination with heavy metals, emphasizing their role in the metal extraction or stabilization in the soil. The aims of this study were to measure the concentrations of Cr, Mn, and Ni in the soils and plants and to elucidate the phytoremediation potential of the studied plants. This study was performed at an abandoned site of serpentine mining in eastern Taiwan. Seven plant species were collected for analysis of Cr, Mn, and Ni, including Crotalaria micans, Miscanthus floridulus, Leucaena leucocephala, Bidens pilosa, Pueraria lobata, Melilotus indicus, and Conyza canadensis. The Cr and Ni concentrations in all studied plants were higher than those in general plants. In all species, the mean concentrations of Cr, Mn, and Ni in the shoots were lower than those in the root. None of the collected specimens exhibited hyperaccumulation of Cr, Mn, and Ni. All studied species may be used to remediate contaminated soils through phytostabilization of Cr and Mn, whereas M. floridulus and M. indicus are appropriate plants for phytostabilization of Ni. However, C. micans, L. leucocephala, B. pilosa, P. lobata, and C. canadensis have the potential to remove Ni from contaminated soils for the purpose of phytoextraction.  相似文献