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21.
Analysis of landslide dam geometries 总被引:2,自引:1,他引:1
The geometry of a landslide dam is an important component of evaluating dam stability. However, the geometry of a natural
dam commonly cannot be obtained immediately with field investigations due to their remote locations. A rapid evaluation model
is presented to estimate the geometries of natural dams based on the slope of the stream, volume of landslides, and the properties
of the deposit. The proposed model uses high resolution satellite images to determine the geometry of the landside dam. These
satellite images are the basic information to a preliminary stability analysis of a natural dam. This study applies the proposed
method to two case studies in Taiwan. One is the earthquake-induced Lung-Chung landslide dam in Taitung, and the second is
the rainfall-induced Shih-Wun landslide dam in Pingtung. 相似文献
22.
D. E. Roa R. K. Smither X. Zhang K. Nie Y. Y. Shieh N. S. Ramsinghani N. Milne J. V. Kuo J. L. Redpath M. S. A. L. Al-Ghazi P. Caligiuri 《Experimental Astronomy》2005,20(1-3):229-239
The objective of this project is to develop and construct an innovative imaging system for nuclear medicine and molecular imaging that uses photon diffraction and is capable of generating 1–2 mm spatial resolution images in two or three dimensions. The proposed imaging system would be capable of detecting radiopharmaceuticals that emit 100–200 keV gamma rays which are typically used in diagnostic nuclear medicine and in molecular imaging. The system is expected to be optimized for the 140.6 keV gamma ray from a Tc-99m source, which is frequently used in nuclear medicine. This new system will focus the incoming gamma rays in a manner analogous to a magnifying glass focusing sunlight into a small focal point on a detector's sensitive area. Focusing gamma rays through photon diffraction has already been demonstrated with the construction of a diffraction lens telescope for astrophysics and a scaled-down lens for medical imaging, both developed at Argonne National Laboratory (ANL). In addition, spatial resolutions of 3 mm have been achieved with a prototype medical lens. The proposed imaging system would be comprised of an array of photon diffraction lenses tuned to diffract a specific gamma ray energy (within 100–200 keV) emitted by a common source. The properties of photon diffraction make it possible to diffract only one specific gamma ray energy at a time, which significantly reduces scattering background. The system should be sufficiently sensitive to the detection of small concentrations of radioactivity that can reveal potential tumor sites at their initial stages of development. Moreover, the system's sensitivity would eliminate the need for re-injecting a patient with more radiopharmaceutical if this patient underwent a prior nuclear imaging scan. Detection of a tumor site at its inception could allow for an earlier initiation of treatment and wider treatment options, which can potentially improve the chances for cure. 相似文献
23.
Movement of deep-seated rainfall-induced landslide at Hsiaolin Village during Typhoon Morakot 总被引:1,自引:0,他引:1
Yu-Shu Kuo Yuan-Jung Tsai Yu-Shiu Chen Chjeng-Lun Shieh Kuniaki Miyamoto Takahiro Itoh 《Landslides》2013,10(2):191-202
This study analyzes the mechanism of the landslide event at Hsiaolin Village during Typhoon Morakot in 2009. This landslide event resulted in 400 deaths. The extremely high intensity and accumulative rainfall events may cause large-scale and complex landslide disasters. To study and understand a landslide event, a combination of field investigations and numerical models is used. The landslide area is determined by comparing topographic information from before and after the event. Physiographic parameters are determined from field investigations. These parameters are applied to a numerical model to simulate the landslide process. Due to the high intensity of the rainfall event, 1,675 mm during the 80 h before the landslide event, the water content of soil was rapidly increased causing a landslide to occur. According to the survivors, the total duration of the landslide run out was less than 3 min. Simulation results indicated that the total duration was about 150 s. After the landslide occurrence, the landslide mass separated into two parts by a spur at EL 590 in about 30 to 50 s. One part passed the spur in about 30 to 60 s. One part inundated the Hsiaolin Village and the other deposited at a local river channel and formed a landslide dam. The landslide dam had height between 50 and 60 m and length between 800 and 900 m. The simulation result shows that the proposed model can be used to evaluate the potential areas of landslides induced by extremely high intensity rainfall events. 相似文献
24.
Yuch-Ning Shieh Henry P. Schwarcz Denis M. Shaw 《Contributions to Mineralogy and Petrology》1976,54(1):1-16
The Loon Lake pluton in the Grenville province of Southeastern Ontario consists of a quartz monzonite rim surrounding a monzonite core containing inclusions of gneiss, gabbro and diorite. The pluton was emplaced in amphibolite facies Apsley gneiss, amphibolite and marble. Abnormally high 18O values are observed in all igneous rock types: quartz monzonite (8.9–13.9), monzonite (8.9–9.7), diorite-gabbro (8.0–9.3). High 18O contents are attributable to interaction between pluton and country rocks, through either isotopic exchange or direct mixing of mobilizate anatectically produced in the contact aureole of the pluton.The Apsley gneiss displays a 18O range from 8.3 to 16.9. There is no difference in 18O distribution between rocks inside and outside the contact aureole, although intermineral isotopic fractionations in the aureole are smaller than those outside. A chemical composition discriminant function that distinguishes rocks of igneous origin (DF>0) from sedimentary (DF<0) is inversely correlated with 18O of the gneisses, indicating that low 18O values are inherited from a silicic volcanic protolith. Al2O3/Na2O, an index of maturity of sediments, increases with 18O for the DF<0 group but is almost constant for the DF>0 group over a 18O range from 8.3 to 13.4. The DF<0 group is inferred to have formed from a series of clastic sediments of varying degree of weathering or maturity; the DF>0 group formed either from tuffs partially altered to zeolites, or from hydrated volcanic flows or ignimbrites. 相似文献
25.
Edward D. Young Joseph L. Wooden Yuch-Ning Shieh Daniel Farber 《Contributions to Mineralogy and Petrology》1992,110(1):68-86
Late Jurassic dioritic plutons from the Bristol Lake region of the eastern Mojave Desert share several geochemical attributes with high-alumina basalts, continental hawaiite basalts, and high-K are andesites including: high K2O concentrations; high Al2O3 (16–19 weight %); elevated Zr/TiO2; LREE (light-rare-earth-element) enrichment (La/YbCN=6.3–13.3); and high Nb. Pearce element ratio analysis supported by petrographic relations demonstrates that P, Hf, and Zr were conserved during differentiation. Abundances of conserved elements suggest that dioritic plutons from neighboring ranges were derived from similar parental melts. In the most voluminous suite, correlated variations in elemental concentrations and (87Sr/86Sr)i indicate differentiation by fractional crystallization of hornblende and plagioclase combined with assimilation of a component characterized by abundant radiogenic Sr. Levenberg-Marquardt and Monte Carlo techniques were used to obtain optimal solutions to non-linear inverse models for fractional crystallization-assimilation processes. Results show that the assimilated material was chemically analogous to lower crustal mafic granulites and that the mass ratio of contaminant to parental magma was on the order of 0.1. Lack of enrichment in 18O with differentiation is consistent with the model results. Elemental concentrations and O, Sr, and Nd isotopic data point to a hydrous REE-enriched subcontinental lithospheric source similar to that which produced some Cenozoic continental hawaiites from the southern Cordillera. Isotopic compositions of associated granitoids suggest that partial melting of this subcontinental lithosphere may have been an important process in the development of the Late Jurassic plutonic arc of the eastern Mojave Desert. 相似文献
26.
27.
Mingda Lv Xi Liu Sean R. Shieh Tianqi Xie Fei Wang Clemens Prescher Vitali B. Prakapenka 《Physics and Chemistry of Minerals》2016,43(4):301-306
Using a diamond-anvil cell and synchrotron X-ray diffraction, the compressional behavior of a synthetic qandilite Mg2.00(1)Ti1.00(1)O4 has been investigated up to about 14.9 GPa at 300 K. The pressure–volume data fitted to the third-order Birch–Murnaghan equation of state yield an isothermal bulk modulus (K T0) of 175(5) GPa, with its first derivative \(K_{T0}^{{\prime }}\) attaining 3.5(7). If \(K_{T0}^{{\prime }}\) is fixed as 4, the K T0 value is 172(1) GPa. This value is substantially larger than the value of the adiabatic bulk modulus (K S0) previously determined by an ultrasonic pulse echo method (152(7) GPa; Liebermann et al. in Geophys J Int 50:553–586, 1977), but in general agreement with the K T0 empirically estimated on the basis of crystal chemical systematics (169 GPa; Hazen and Yang in Am Miner 84:1956–1960, 1999). Compared to the K T0 values of the ulvöspinel (Fe2TiO4; ~148(4) GPa with \(K_{T0}^{{\prime }} = 4\)) and the ringwoodite solid solutions along the Mg2SiO4–Fe2SiO4 join, our finding suggests that the substitution of Mg2+ for Fe2+ on the T sites of the 4–2 spinels can have more significant effect on the K T0 than that on the M sites. 相似文献
28.
Shuangmeng Zhai Yuan Yin Sean R. Shieh Shuangming Shan Weihong Xue Ching-Pao Wang Ke Yang Yuji Higo 《Physics and Chemistry of Minerals》2016,43(4):307-314
In situ high-pressure synchrotron X-ray diffraction and Raman spectroscopic studies of orthorhombic CaFe2O4-type β-CaCr2O4 chromite were carried out up to 16.2 and 32.0 GPa at room temperature using multi-anvil apparatus and diamond anvil cell, respectively. No phase transition was observed in this study. Fitting a third-order Birch–Murnaghan equation of state to the P–V data yields a zero-pressure volume of V 0 = 286.8(1) Å3, an isothermal bulk modulus of K 0 = 183(5) GPa and the first pressure derivative of isothermal bulk modulus K 0′ = 4.1(8). Analyses of axial compressibilities show anisotropic elasticity for β-CaCr2O4 since the a-axis is more compressible than the b- and c-axis. Based on the obtained and previous results, the compressibility of several CaFe2O4-type phases was compared. The high-pressure Raman spectra of β-CaCr2O4 were analyzed to determine the pressure dependences and mode Grüneisen parameters of Raman-active bands. The thermal Grüneisen parameter of β-CaCr2O4 is determined to be 0.93(2), which is smaller than those of CaFe2O4-type CaAl2O4 and MgAl2O4. 相似文献
29.
Oxygen and hydrogen isotope studies of contact metamorphism in the Santa Rosa Range,Nevada and other areas 总被引:1,自引:0,他引:1
The O18/O16 and D/H ratios have been determined for rocks and coexisting minerals from several granitic plutons and their contact metamorphic aureoles in the Santa Rosa Range, Nevada, and the Eldora area, Colorado, with emphasis on pelitic rocks. A consistent order of O18/O16 and D/H enrichment in coexisting minerals, and a correlation between isotopic fractionations among coexisting mineral pairs are commonly observed, suggesting that mineral assemblages tend to approach isotopic equilibrium during contact metamorphism. In certain cases, a systematic decrease is observed in the oxygen isotopic fractionations of mineral pairs as one approaches the intrusive contacts. Isotopic temperatures generally show good agreement with heat flow considerations. Based on the experimentally determined quartz-muscovite O18/O16 fractionation calibration curve, temperatures are estimated to be 525 to 625° C at the contacts of the granitic stocks studied.Small-scale oxygen isotope exchange effects between intrusive and country rock are observed over distances of 0.5 to 3 feet on both sides of the contacts; the isotopic gradients are typically 2 to 3 per mil per foot. The degree of oxygen isotopic exchange is essentially identical for different coexisting minerals. This presumably occurred through a diffusion-controlled recrystallization process. The size of the oxygen isotope equilibrium system in the small-scale exchanged zones varies from about 1.5 to 30 cm. A xenolith and a re-entrant of country rock projecting into an intrusive have both undergone much more extensive isotopic exchange (to hundreds of feet); they also show higher isotopic temperatures than the rocks in the aureole. The marginal portions of most plutons have unusually high O18/O16 ratios compared to normal igneous rocks, presumably due to large-scale isotopic exchange with metasedimentary country rocks when the igneous rocks were essentially in a molten state. The isotopic data suggest that outward horizontal movement of H2O into the contact metamorphic aureoles is very minor, but upward movement of H2O is important. Also, direct influx and absorption of H2O from the country rock appears to have occurred in certain intrusive stocks. The D/H ratios of biotites in the contact metamorphic rocks and their associated intrusions show a geographic correlation that is similar to that shown by the D/H ratios of meteoric surface waters, perhaps indicating that meteoric waters were present in the rocks during crystallization of the biotites.Except in the exchanged zones, the O18/O16 ratios of pelitic rocks do not change appreciably during contact metamorphism, even in the cordierite and sillimanite grades; this is in contrast to regional metamorphic rocks which commonly decrease in O18 with increasing grade. Thus, contact metamorphic rocks generally do not exchange with large quantities of igneous H2O, but regional metamorphic rocks appear to have done so.Publications of the Division of Geological Sciences, California Institute of Technology, Contribution No. 1565. 相似文献
30.