Developing serpent-type wave generators to create solitary wave simulations with BEM     

Wen-Kai Weng  Ruey-Syan Shih  Chung-Ren Chou 《中国海洋工程》2013,27(5):671-682

  相似文献   

A reply to [a discussion of shih and Komar's (1990) analysis of differential bedload transport rates in a gravel-bed stream: A grain-size distribution approach] by P. Diplas     

Paul D. Komar  Shyuer-Ming Shih 《地球表面变化过程与地形》1992,17(6):633-634

  相似文献   

Uniform heat flow in a semi-infinite medium disturbed by a body of different thermal conductivity     

Keh-Gong Shih 《Pure and Applied Geophysics》1971,85(1):298-308

Summary The approximate solution for the disturbance of a uniform heat flow in a homogeneous semi-infinite medium by an object of different thermal conductivity buried in it is generally used in the interpretation of heat flow anomalies on the ocean bottom. In order to know the accuracy of the approximate solution, a comparison between the approximate solution and the exact solution is given in the case of a very long horizontal cylinder in a semi-infinite medium. The computed results indicate that the two solutions agree to within 10% whend>1.3 and 0.5<<2, whered is ratio of the depth to the radiusR ₀ of the cylinder and is the factor of the contrast of the thermal conductivities between the medium and the body. As for the cases when 1 and 1, the same accuracy can be obtained only whend>2. A similar approach is also applied to the case of a spherical conductor in a semi-infinite medium by using a bispherical harmonic solution. The results of both the bipolar solution and the bispherical solution show that when 1 andd1, the vertical thermal gradient at the surface of the semi-infinite medium is always positive and tends to zero, but a negative vertical gradient may be obtained for the approximate solutions.  相似文献   

Mercury,organic-mercury and selenium in small cetaceans in Taiwanese waters     

Chen MH  Shih CC  Chou CL  Chou LS 《Marine pollution bulletin》2002,45(1-12):237-245

Total Hg (∑Hg), organic-Hg (O-Hg) and Se bioaccumulations in small cetaceans distributed in Taiwanese waters of the Taiwan Strait and the southwestern Pacific have been investigated for the first time. The results could represent the baseline metal concentrations of marine mammals in the southwestern Pacific, where volcanic activities are possibly the major source of mercury to the environments. Muscle samples of four species of small cetaceans were collected from animals accidentally caught by tuna-longline fisheries from 1994 through 1995. In total, 53 pantropical spotted dolphins, Stenella attenuata, nine spinner dolphins, S. longirostris, five bottlenose dolphins, Turiops truncatus and four Risso's dolphins, Grampus giseus were analyzed. In addition, two stranded pantropical spotted dolphins were investigated. Cold vapour AAS and ICP-MS were used in the analysis of Hg and Se, respectively. Significant species difference was found in the four species of small cetaceans. Among them, the pantropical spotted dolphin showed the highest mean concentration (mg/kg wet wt.) of both ∑Hg (3.64±2.19) and O-Hg (2.79±1.23), whereas the Risso's dolphin had the highest mean concentrations of Se (1.77±1.29). There was no significant sex difference with respect to metal bioaccumulation in the samples of S. attenuata. Significant correlations between body length (BL) and ∑Hg, as well as O-Hg concentrations were observed in pantropical spotted (Sa) and spinner dolphins (Sl). The linear relationships were Sa: ∑Hg=−8.290+0.066BL, r=0.421; Sl: ∑Hg=−2.735+0.025BL, r=0.875; Sa: O-Hg=−3.723+0.036BL, r=0.408; and Sl: O-Hg=−3.017+0.025BL, r=0.870. However, a demethylation phenomenon that decreasing the percentage of O-Hg coupled with increasing levels of Se was observed when the ∑Hg concentrations in the muscle tissues of dolphins reached 4 mg/kg wet wt.  相似文献   

Spectral analysis of water level fluctuations in aquifers     

D. C.-F. Shih  G.-F. Lin 《Stochastic Environmental Research and Risk Assessment (SERRA)》2002,16(5):374-398

 The water level of a seawater gauging station and 18 groundwater wells coupled with atmospheric pressure in southwestern Taiwan are analyzed by using spectral analysis in time and frequency domain. The semidiurnal component is found to be the most significant signal from the measurement of water level and atmospheric pressure, and the diurnal component is less distinctive in part of water level and atmospheric pressure record. Although auto-spectral and cross-spectral density functions are significant in atmospheric pressure and water level, the pressure variations do not significantly affect the seawater and the majority of groundwater level in the study area with amplitude of time series observations. The astronomical tidal components are likely the main factor causing seawater and groundwater level to fluctuate in Pingtung, Taiwan. Time lags are estimated from 20 min to a few hours in aquifers. It concludes that the disturbance on groundwater levels from the effect of oceanic astronomical tide is different from the varying hydrogeological characteristics of aquifer. In this study, the spectral analysis of water level in time and frequency domains gives strong indications of sensitive variations to water level fluctuation. This research is supported by the Institute of Nuclear Energy Research (INER), AEC, Taiwan, Republic of China, under a fund from Executive Yuan. The authors thank Taiwan Central Weather Bureau and Taiwan Provincial Government Water Resources Department for providing useful data.  相似文献   

Identification of phase propagation of water level in tidal river by spectral analysis     

D. C.-F. Shih 《Stochastic Environmental Research and Risk Assessment (SERRA)》2002,16(6):449-463

 Water levels of the five river stages in the Taipei Basin are analyzed by using spectral analysis in time-frequency domain through one-year hourly data. The autospectral and cross-spectral density function, coherence, phase angle and associated statistic parameters are studied. The semi-diurnal, diurnal and quarter-diurnal tidal components are significant for river stages, which are also apparently related to astronomical tides of M₂, S₂, N₂, S₁, O₁ and M₄, MK₄ or MS₄ respectively. The time lags versus propagation distance are shown as linear distribution for two stream systems. The time lags are 3.2, 4.0 and 2.5 (h) for semi-diurnal, diurnal and quarter-diurnal components in Tanshui River – Tanhan Stream system, while 3.5, 3.5 and 2.2 (h) in Tanshui River – Hsintien Stream system. This research was supported by the Institute of Nuclear Energy Research(INER), Atomic Energy Council, Taiwan, Republic of China, under the fund of the Executive Yuan. The author appreciates Taiwan Provincial Government Water Resources Department and Central Weather Bureau for providing useful data.  相似文献   

Role of fluids in surface deformation caused by the 1999 Chi‐Chi earthquake in Taiwan     

Jiin‐Shuh Jean  Chuan‐Cheng Liu  Wei‐Teh Jiang  Jinder Chow  Ting‐To Yu  Ching‐Weei Lin  Shih‐Wei Huang 《地球表面变化过程与地形》2002,27(1):1-10

The 1999 Chi‐Chi earthquake significantly altered the landscape of central Taiwan. Surface deformation produced by the earthquake along the trace of the Chelungpu thrust can be classified into two styles: (1) uplift without significant surface rupture, and (2) uplift accompanied by surface rupture. Here we examine areas that exhibited the first style of deformation (e.g. Wufeng). Seismic stress at the time of the main shock may have been relieved by high pore‐fluid pressure in a 300‐m‐thick sand and gravel aquifer. Along the thrust fault, frictional heating of these sediments resulted in thermal expansion and an increase in pore‐fluid pressure. High pore‐fluid pressure damped seismic‐wave energy and enhanced intergranular slips of unconsolidated sandy and gravel sediments, which were possibly assisted by sulphuric acid corrosion, leading to a high sulphate content in the groundwater (c. 70 mg L^?1). These changes permitted surface folding and terrace‐style uplifting to occur without significant rupture. In contrast, other areas in which the second style of deformation is dominant (e.g. Fengyuen‐Shihkang) have thin (0–10 m) sand and gravel deposits and lower concentrations of sulphate (c. 30 mg L^?1) in groundwater. In these areas, sediments were heated but not sufficiently to produce significant thermal expansion and increase in pore‐fluid pressure; accumulation of stress in these locations led to rupture at the ground surface, with the formation of steep fault scarps. The areas exhibiting the first deformation style are characterized by the presence of high pore‐fluid pressure, frictional heat conduction, and possibly chemical corrosion related to sulphuric acid attack and formation of sulphate, in contrast to those involving significant uplift and surface rupture. The areal distribution of these two surface deformation styles suggests that the aforementioned fluid‐related subsurface processes may have altered the characteristics of sediments and caused diverse responses to the quake. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Large earthquake-triggered landslides and mountain belt erosion: The Tsaoling case,Taiwan     

Rou-Fei Chen  Yu-Chang Chan  Jacques Angelier  Jyr-Ching Hu  Chung Huang  Kuo-Jen Chang  Tian-Yuan Shih 《Comptes Rendus Geoscience》2005,337(13):1164-1172

The 1999 Chi-Chi earthquake triggered the catastrophic Tsaoling landslide in central Taiwan. We mapped the landslide area and estimated the landslide volume, using high-resolution digital elevation model from airborne LiDAR (Light Detection and Ranging), satellite images, aerial photographs and topographic maps. The comparison between cut and fill volumes, about 0.126 and 0.150 km³, respectively, suggests a volume increase of 19% due to decompaction during landsliding. In April 2002, the cut and fill volumes were about 0.137 and 0.116 km³, respectively. These estimates suggest that 2.5 years after the event, the volume of landslide debris removed by river erosion was nearly 0.045 km³. Such a large value highlights the importance of landslide processes for erosion and long-term denudation in the Taiwan mountain belt. To cite this article: R.-F. Chen et al., C. R. Geoscience 337 (2005).  相似文献   

Effects of jpeg 2000 compression on automated dsm extraction: evidence from aerial photographs   总被引：1，自引：0，他引：1  

Tian-Yuan  Shih  Jung-Kuan  Liu 《The Photogrammetric Record》2005,20(112):351-365

This paper evaluates the effects of JPEG 2000 compression on automated digital surface model (DSM) extraction, using the area-based matching technique. Two stereopairs of aerial photographs, which have different photo scale, pixel size, and topographic type, are used as the images for the experiments. In the experiments, the DSM generated from the uncompressed image is set as the reference, and the elevation accuracy is computed for a range of compression ratios (2:1 to 100:1). The results show that the employed indices of image quality based on the JPEG 2000 compression are clearly superior to the commonly used JPEG compression technique—especially for high compression ratios. However, the elevation accuracy varies with the compression ratios. Also, JPEG 2000 compression does not have a significant influence on the percentage of the successful matching rate. In addition, a near linear fall-off is observed in extracted DSM accuracy with increasing compression ratios.  相似文献   

Differential bedload transport rates in a gravel-bed stream: A grain-size distribution approach     

Shyuer-Ming Shih  Paul D. Komar 《地球表面变化过程与地形》1990,15(6):539-552

The grain-size distributions of bedload gravels in Oak Creek, Oregon, follow the ideal Rosin distribution at flow stages which exceed that necessary to initiate breakup of the pavement in the bed material. The distributions systematically vary with flow discharge and bed stress, such that at higher flow stages the grain sizes are coarser while the spread of the distribution decreases. A differential bedload transport function for individual grain-size fractions is formulated utilizing the dependence of the two parameters in the Rosin distribution on the flow stress. The total transport rate, which is also a function of the flow stress, is apportioned within the Rosin grain-size distribution to yield the fractional transport rates. The derived bedload function has the advantage of yielding smooth, continuous frequency distributions of transport rates for the grain-size fractions, in contrast to the discrete transport functions which predict rates for specified sieve fractions. Successful reproduction of the measured fractional transport rates and bedload grain-size distributions in Oak Creek by this approach demonstrates its potential for evaluations of transport rates of size fractions in gravel-bed streams. The approach will be useful in investigations of downstream changes in bed material grain-size distributions.  相似文献