Lateral response of dams in semi-elliptical rigid canyons   总被引：2，自引：0，他引：2  

P. Dakoulas  C. Hsu 《Soil Dynamics and Earthquake Engineering》1993,12(8):497-507

An analytical closed-form solution is developed for the lateral response of earth and rockfill dams built in semi-elliptical canyons. The dam is idealized as a linearly hysteretic elastic body deforming only in shear, whereas the canyon is assumed to be rigid. The solution for the dam response is given in terms of prolate spheroidal radial and angular functions of the first kind and zero order. Results are presented for natural frequencies, modal displacement shapes, participation factors, and response to transient and steady-state harmonic base excitation for various dam length-to-height ratios. Comparisons are made of the effects of the length-to-height ratio and the canyon shape on the response of dams built in semi-elliptical and rectangular canyons. A subsequent study (Dakoulas, P. & Hsu, C.H., Response of earth dams in semi-elliptical flexible canyons to oblique SH waves, Report, Rice University, Houston, Texas, 1993) extends this model to a semi-elliptical canyon consisting of flexible elastic rock, subjected to obliquely incident harmonic SH waves.  相似文献   

Earthquake strong motions recorded by a large near-source array of digital seismographs     

B. A. Bolt  Y. B. Tsai  K. Yeh  M. K. Hsu 《地震工程与结构动力学》1982,10(4):561-573

Specially designed arrays of strong-motion seismographs near to the earthquake source are required for seismological and engineering studies of the generation and near-field properties of seismic waves. The first such large digital array, called SMART 1 (with radius 2 km and 37 accelerometers), to record substantial ground motion (up to 0·24g horizontal acceleration) became operational in late 1980 in a highly seismic region of Taiwan. During the first 6 months of operation, SMART 1 recorded nine earthquakes with magnitudes ranging from M_L 3·8 to 6·9. Three were located directly below the array at focal depths of 59 to 76 km. The remaining six had shallow depths and epicentral distances from 7 to 193 km. Digital records from 27 three-component accelerographs were obtained from a magnitude 6·9 (M_L) local earthquake on 29 January 1981. Representative measurements are described of seismic wave coherency and power spectrum as a function of wave number, frequency, azimuth of propagation and wave type. Acceleration waveforms varied significantly across the array for each event. On average, peak acceleration of horizontal components was about three times that of the vertical component. Relative spectral changes from earthquake to earthquake were large.  相似文献   

By-products of oxidative biocides: Toxicity to oyster larvae     

M.E. Stewart  W.J. Blogoslawski  R.Y. Hsu  G.R. Helz 《Marine pollution bulletin》1979,10(6):166-169

Selected by-products which are produced upon chlorination or ozonization of seawater were examined for their effect on eastern oyster (Crassostrea virginica) larvae. The compounds, bromate, bromoform, and chloroform, were studied at 0.05, 0.1, 1.0, and 10.0 mg/l. Repeated bioassays indicated that even at these low levels, all three substances produced some larval mortality. This preliminary study suggests that oxidation by-products formed during chlorination or ozonization of power plant cooling waters may have adverse effects upon the growth of marine invertebrates, such as C. virginica, during their delicate larval stages.  相似文献   

Al‐Mg systematics of CAIs,POI, and ferromagnesian chondrules from Ningqiang     

Weibiao Hsu  Gary R. Huss  G. J. Wasserburg 《Meteoritics & planetary science》2003,38(1):35-48

Abstract— We have made aluminum‐magnesium isotopic measurements on 4 melilite‐bearing calcium‐aluminum‐rich inclusions (CAIs), 1 plagioclase‐olivine inclusion (POI), and 2 ferromagnesian chondrules from the Ningqiang carbonaceous chondrite. All of the CAIs measured contain clear evidence for radiogenic ²⁶Mg* from the decay of ²⁶Al ( = 1.05 Ma). Although the low Al/Mg ratios of the melilites introduce large uncertainties, the inferred initial ²⁶Al/²⁷Al ratios for the CAIs are generally consistent with the value of 5 times 10^?5. There is clear evidence of ²⁶Al* in one POI and two chondrules, but with considerable uncertainties in the value of (²⁶Al/²⁷Al)₀. The (²⁶Al/²⁷Al)₀ ratios for the POI and the chondrules are 0.3–0.6 times 10^?5, roughly an order of magnitude lower than the canonical value. Ningqiang shows very little evidence of metamorphism as a bulk object and the (²⁶Al/²⁷Al)₀ ratios in its refractory inclusions and chondrules are consistent with those found in other unmetamorphosed chondrites of several different classes. Our observations and those of other workers support the view that ²⁶Al was widely and approximately homogeneously distributed throughout the condensed matter of the solar system. The difference in (²⁶Al/²⁷Al)₀ between CAIs and less refractory materials seems reasonably interpreted in terms of a ～2 million year delay between the formation of CAIs and the onset of formation of less refractory objects. The POI shows clear differences in ²⁵Mg/²⁴Mg between its constituent spinels and olivine, which confirms that they are partially reprocessed material from different sources that were rapidly quenched.  相似文献   

Correlation and dating of Quaternary alluvial-fan surfaces using scarp diffusion     

Leslie Hsu  Jon D. Pelletier 《Geomorphology》2004,60(3-4):319-335

Great interest has recently been focused on dating and interpreting alluvial-fan surfaces. As a complement to the radiometric methods often used for surface-exposure dating, this paper illustrates a rapid method for correlating and dating fan surfaces using the cross-sectional shape of gullies incised into fan surfaces. The method applies a linear hillslope-diffusion model to invert for the diffusivity age, κt (m²), using an elevation profile or gradient (slope) profile. Gullies near the distal end of fan surfaces are assumed to form quickly following fan entrenchment. Scarps adjacent to these gullies provide a measure of age. The method is illustrated on fan surfaces with ages of approximately 10 ka to 1.2 Ma in the arid southwestern United States. Two areas of focus are Death Valley, California, and the Ajo Mountains piedmont, Arizona. Gully-profile morphology is measured in two ways: by photometrically derived gradient (slope) profiles and by ground-surveyed elevation profiles. The κt values determined using ground-surveyed profiles are more consistent than those determined using photo-derived κt values. However, the mean κt values of both methods are comparable. The photometric method provides an efficient way to quantitatively and objectively correlate and relatively-date alluvial-fan surfaces. The κt values for each surface are determined to approximately 30–50% accuracy.  相似文献   

Coastal Gravity Anomalies from Retracked Geosat/GM Altimetry: Improvement, Limitation and the Role of Airborne Gravity Data   总被引：6，自引：0，他引：6  

Cheinway Hwang  Jinyun Guo  Xiaoli Deng  Hsin-Ying Hsu  Yuting Liu 《Journal of Geodesy》2006,80(4):204-216

We process geophysical and waveform data records of the Geosat/GM (geodetic mission) satellite altimeter mission for waveform retracking and applications. An improved threshold retracker is developed. The performances of the Beta-5, threshold and improved threshold retrackers are assessed over waters around Taiwan. The improved threshold retracker outperforms the other two. The improvement in the accuracy of sea surface height (SSH) is investigated according to marine zone and the distance of waters to the shore. The improvement rate increases closer to the land, with the largest improvement rate of about 20% in waters within 10 km of the shore. Over waters around islands and coasts, there are still retracked SSHs with large errors. Least-squares collocation is used to compute gravity anomalies from the Geosat/GM altimeter data. Use of retracked SSHs improves the accuracy of gravity anomalies by about 11%. Adding airborne gravity data further improves the accuracy, especially in the immediate vicinity of the coasts. Tide model errors over coastal waters remain a problem in altimetry applications, even if the waveforms are properly retracked.  相似文献   

A new family of orthonormal wavelet bases     

L. T. Liu  H. T. Hsu  B. X. Gao 《Journal of Geodesy》1998,72(5):294-303

In this contribution we introduce the concept of multiresolution analysis (MRA) and give an explanation of the relationship between MRA and orthonormal wavelet basis. The construction of the orthonormal B-spline wavelet bases is described in detail. We extend the B-splines to `non-integral order' cases and thus obtain a new family of orthonormal wavelet bases for the space L ²(R). Some good properties of the new wavelets are demonstrated. The new wavelet family gives satisfactory performances in our research projects including seismic signal compression and gravity tide data processing. Received: 19 July 1996 / Accepted: 17 November 1997  相似文献   

Plan for a groundwater monitoring network in Taiwan     

Shiang-Kueen Hsu 《Hydrogeology Journal》1998,6(3):405-415

 In Taiwan, rapid economic growth, rising standards of living, and an altered societal structure have in recent years put severe demands on water supplies. Because of its stable quantity and quality, groundwater has long been a reliable source of water for domestic, agricultural, and industrial users, but the establishment of a management program that integrates groundwater and surface-water use has been hampered by the lack of groundwater data. In 1992, the Department of Water Resources (DWR) initiated a program entitled "Groundwater Monitoring Network Plan in Taiwan." Under this program, basic groundwater data, including water-level and water-quality data, are being collected, and a reliable database is being established for the purpose of managing total water resources. This paper introduces the goals, implementation stages, and scope of that plan. The plan calls for constructing 517 hydrogeologic survey stations and 990 groundwater monitoring wells within 17 years. Under this program, water-level fluctuations are continuously monitored, whereas water-quality samples are taken for analysis only at the initial drilling stage and, subsequently, at the time when a monitoring well is being serviced. In 1996, the DWR and the Water Resources Planning Commission were merged to form today's Water Resources Bureau. Received, July 1997 · Revised, February 1998 · Accepted, January 1998  相似文献   

南华夏造山带构造演化的新证据   总被引：40，自引：6，他引：40       下载免费PDF全文

李继亮  许靖华 《地质科学》1989,2(3):217-225

华南的大地构造有两种解释,一种可称为加里东造山模式,另一种可称为华南阿尔卑斯模式。前者认为华南是一个早古生代造山带,其后便成为准地台。中生代时受到活化导致盖层与基底的褶皱、断裂、岩浆作用和成矿作用。但这个模式不能解释许多地质事实。 本文继许靖华等(1987)的模式之后,给出了一些新证据,其中包括皖赣蛇绿混杂岩、蓝田、西山和乐平构造窗以及庐山飞来峰。这些证据为华南的三叠纪造山作用和构造演化模式提供了强有力的支持。  相似文献   

Mineralogy of silicate inclusions of the Colomera IIE iron and crystallization of Cr-diopside and alkali feldspar from a partial melt     

Hiroshi Takeda  Weibiao Hsu  Gary R. Huss 《Geochimica et cosmochimica acta》2003,67(12):2269-2287

We studied the mineralogy, mineral chemistry, and compositions of 48 interior silicate inclusions and a large K-rich surface inclusion from the Colomera IIE iron meteorite. Common minerals in the interior silicate inclusions are Cr diopside and Na plagioclase (albite). They are often enclosed by or coexist with albitic glasses with excess silica and minor Fe-Mg components. This mineral assemblage is similar to the “andesitic” material found in the Caddo County IAB iron meteorite for which a partial melt origin has been proposed. The fairly uniform compositions of Cr diopside (Ca₄₄Mg₄₆Fe₁₀) and Na plagioclase (Or_2.5Ab_90.0An_7.5 to Or_3.5Ab_96.1An_0.4) in Colomera interior inclusions and the angular boundaries between minerals and metal suggest that diopside and plagioclase partially crystallized under near-equilibrium conditions from a common melt before emplacement into molten metal. The melt-crystal assemblage has been called “crystal mush.” The bulk compositions of the individual composite inclusions form an array between the most diopside-rich inclusion and plagioclase. This is consistent only with a simple mechanical mixing relationship, not a magmatic evolution series. We propose a model in which partly molten metal and crystal mush were mixed together by impact on the IIE parent body. Other models involving impact melting of the chondritic source material followed by growth of diopside and plagioclase do not easily explain near equilibrium growth of diopside and Na plagioclase, followed by rapid cooling. In the K-rich surface inclusion, K feldspar, orthopyroxene, and olivine were found together with diopside for the first time. K feldspar (sanidine, Or_92.7Ab_7.2An_0.1 to Or_87.3Ab_11.0An_1.7) occurs in an irregular veinlike region in contact with large orthopyroxene crystals of nearly uniform composition (Ca_1.3Mg_80.5Fe_17.8 to Ca_3.1Mg_78.1Fe_18.9) and intruding into a relict olivine with deformed-oval shape. Silica and subrounded Cr diopside are present within such K-feldspar regions. Some enrichments of the albite component have been detected at the end of curved elongated nodules of K feldspar intruded into the mafic silicates. The textural relationships suggest that a K-rich melt was present. A K-rich melt is neither the first melt of a chondritic system nor a differentiation product of a Na-rich partial melt of chondritic material. The K-rich material may have originated as a fluid phase that leached K from surrounding materials and segregated by a mechanism similar to that proposed for the Na-rich inclusions.  相似文献