Non-Circular Rock-Fall Motion Behavior Modeling by the Eccentric Circle Model     

Yi-Long Chang  Chien-Yuan Chen  An-Yuan Xiao 《Rock Mechanics and Rock Engineering》2011,44(4):469-482

The geometry of a block is a major factor affecting its rock-fall motion. A two-dimensional disc or three-dimensional sphere is often used to numerically simulate rock-fall motion, though circular or spherical blocks poorly represent the real geometry of rock falls. An eccentric circle model is specifically proposed to simulate the behavior of non-circular blocks in rock-fall motion using the distinct element method. In the eccentric circle model, the moment originates from the eccentricity. Three types of block shape, circle, ellipse, and eccentric circle, were used to simulate the fall of a single block through four different slope shapes to impact on a defense wall. The results of the simulation revealed that when the eccentricity falls below 0.5, the rock-fall motion is close to that of the ellipse model. As eccentricity grows, the rock-fall motion is closer to that of a flat piece, more stable, and tending to slide. When the block impacts the defensive wall using the circle model, a higher force and energy head in the wall is obtained. This case tends to be conservative, with the exception of the high slope angle case. The bouncing height using the circle model falls just between those of the ellipse and the eccentric circle models and tends to be unconservative. In conclusion, the rock-fall motion simulation using the proposed eccentric circle model appears to approach the non-circular block trajectory and energy loss, making it useful for rock-fall risk prevention and mitigation.  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   

The integration of nautical hazard assessment and harbor GIS models to the Taichung Port area in Taiwan     

Cheng-Wu Chen  Ching-Chung Lee  Chia-Hung Chen  Chun-Pin Tseng 《Natural Hazards》2013,67(2):275-294

Human hazards can represent a significant risk to the population and cause huge economic damage in many urbanized regions. In order to be able to identify risk hot spots and implement targeted risk reduction measures, decision makers need to have a clear picture of the risk situation in their countries or regions. This work reviews existing approaches for human hazard and risk assessment, and geographic information system–based statistical tools are employed to analyze the hazard cases which happened within the Taichung Port area from 2000 to 2010. Based on hazard analysis, we establish a seasonal digital map and calculate the center of the distribution of hazard cases and the standard distance and observe the distribution trend. We also identify the hazard cases’ gathering mode by the average nearest neighbor method. Finally, hot spot analysis is proposed to assess the position and features of hot and cold spots, as a reference for coast guard patrols.  相似文献   

GIS-based evaluation on the fault motion-induced coseismic landslides     

Ming-Wey HUANG  Chien-Yuan CHEN  Tzu-Hsiu WU  Sheu-Yien LIU  Ching-Yun KAO 《山地科学学报》2012,9(5):601-612

Earthquake-induced potential landslides are commonly estimated using landslide susceptibility maps. Nevertheless, the fault location is not identified and the ground motion caused by it is unavailable in the map. Thus, potential coseismic landslides for a specific fault motion-induced earthquake could not be predicted using the map. It is meaningful to incorporate the fault location and ground motion characteristics into the landslide predication model. A new method for a specific fault motion-induced coseismic landslide prediction model using GIS (Geographic Information System) is proposed herein. Location of mountain ridges, slope gradients over 45 o , PVGA (Peak Vertical Ground Accelerations) exceeded 0.15 g, and PHGA (Peak Horizontal Ground Accelerations) exceeded 0.25 g of slope units were representing locations that initiated landslides during the 1999 Chi-Chi earthquake in Taiwan. These coseismic landslide characteristics were used to identify areas where landslides occurred during Meishan fault motion-induced strong ground motions in Chiayi County in Taiwan. The strong ground motion (over 8 Gal in the database, 1 Gal = 0.01 m/s 2 , and 1 g = 981 Gal) characteristics were evaluated by the fault length, site distance to the fault, and topography, and their attenuation relations are presented in GIS. The results of the analysis show that coseismic landslide areas could be identified promptly using GIS. The earthquake intensity and focus depth have visible effects on ground motion. The shallower the focus depth, the larger the magnitude increase of the landslides. The GIS-based landslide predication method is valuable combining the geomorphic characteristics and ground motion attenuation relationships for a potential region landslide hazard assessment and in disaster mitigation planning.  相似文献   

Comparison of metal accumulation in the azooxanthellate scleractinian coral (Tubastraea coccinea) from different polluted environments     

Isani Chan  Jia-Jang Hung  Shao-Hung Peng  Li-Chun Tseng  Tung-Yuan Ho  Jiang-Shiou Hwang 《Marine pollution bulletin》2014

The response of metal accumulation in coral Tubastraea coccinea to various degrees of metal enrichment was investigated from the Yin-Yang Sea (YYS) receiving abandoned mining effluents, the Kueishan Islet (KI) hydrothermal vent field, and the nearshore area of remoted Green Island (GI). The concentrations of most dissolved metals were highest in seawater at YYS, followed by KI, and then GI, showing the effects of anthropogenic and venting inputs on metal levels. Five metals (Co, Fe, Mn, Ni, and Zn) yielded significant differences (p < 0.05) among the skeleton samples. We identified similar patterns in the metal–Ca ratios, indicating that the elevated metals in skeletons was a consequence of external inputs. The coral tissues were relatively sensitive in monitoring metal accumulation, showing significant differences among three locations for Cd, Co, Cu, Fe, Pb, Ni, and Zn. Specific bioconcentration factors provided strong support for the differential metal accumulation in skeletons and tissues.  相似文献   

The topographic signature of a major typhoon          下载免费PDF全文

Chih‐Ming Tseng  Ching‐Weei Lin  Giancarlo Dalla Fontana  Paolo Tarolli 《地球表面变化过程与地形》2015,40(8):1129-1136

In August 2009, the typhoon Morakot, characterized by a cumulative rainfall up to 2884 mm in about three days, triggered thousands of landslides in Taiwan. The availability of LiDAR surveys before (2005) and after (2010) this event offers a unique opportunity to investigate the topographic signatures of a major typhoon. The analysis considers the comparison of slope–area relationships derived by LiDAR digital terrain models (DTMs). This approach has been successfully used to distinguish hillslope from channelized processes, as a basis to develop landscape evolution models and theories, and understand the linkages between landscape morphology and tectonics, climate, and geology. We considered six catchments affected by a different degree of erosion: three affected by shallow and deep‐seated landslides, and three not affected by erosion. For each of these catchments, 2 m DTMs were derived from LiDAR data. The scaling regimes of local slope versus drainage area suggested that for the catchments affected by landslides: (i) the hillslope‐to‐valley transitions morphology, for a given value of drainage area, is shifted towards higher value of slopes, thus indicating a likely migration of the channelized processes and erosion toward the catchment boundary (the catchment head becomes steeper because of erosion); (ii) the topographic gradient along valley profiles tends to decrease progressively (the valley profile becomes gentler because of sediment deposition after the typhoon). The catchments without any landslides present a statistically indistinguishable slope–area scaling regime. These results are interesting since for the first time, using multi‐temporal high‐resolution topography derived by LiDAR, we demonstrated that a single climate event is able to cause significant major geomorphic changes on the landscape, detectable using slope–area scaling analysis. This provides new insights about landscape evolution under major climate forcing. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

The effect of pH on both spectral types of R-phycoerythrin     

Pan Zhongzheng  Zhou Baicheng  Zeng Chengkui  C. K. Tseng 《中国海洋湖沼学报》1987,5(1):73-79

There are two spectral types of R-phycoerythrin (RPE) in red algae. One is the triple peak type RPE with absorption maxima at 498,540 and 565 nm. The other is the double peak type RPE with absorption maxima at 498 and 565 nm, and an absorption shoulder at 540 nm. The former is present only in higher classes of the more advanced Florideophyceae, the latter occurs chiefly in the more primitive Bangiophyceae. When these two types of RPE are treated with buffer solutions with a broad pH range from 2.0 to 11.0, their absorption and fluorescence spectra remain unchanged within the range adjacent to neutral pH. At pH values higher than 9.6, the absorption and fluorescence spectra of triple peak type RPE still remain stable, but the absorption spectra of double peak type RPE produce gradually a protrusion similar to an absorption peak at about 540 nm. This phennomenon shows that there are certain differences in structure between these two types of RPE. Both types of RPE are naturally occurring products showing systematic developmental meaning in red algae. Contribution No. 1333 from the Institute of Oceanology, Academic Sinica.  相似文献