Reconstructed chloride concentration profiles below the seabed in Hong Kong (China) and their implications for offshore groundwater resources   总被引：1，自引：1，他引：0  

Jiu Jimmy Jiao  Lei Shi  Xingxing Kuang  Chun Ming Lee  Wyss W.-S. Yim  Shouye Yang 《Hydrogeology Journal》2015,23(2):277-286

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Finite element simulations of seismic effects on retaining walls with liquefiable backfills     

Mandar M. Dewoolkar  A. H. C. Chan  Hon‐Yim Ko  Ronald Y. S. Pak 《国际地质力学数值与分析法杂志》2009,33(6):791-816

Finite element simulations of two centrifuge tests on the same cantilever retaining wall model holding liquefiable backfill were conducted using the Biot formulation‐based program DIANA–SWANDYNE II. To demonstrate the effects due to different pore fluids in seismic centrifuge experiments, water was used as the pore fluid in one experiment whereas a substitute pore fluid was used in the second experiment. The cantilever wall model parameters were determined by comparing simulations with measurements from free‐vibration tests performed on the model wall without backfill. The initial stress conditions for dynamic analysis for the soil backfill were obtained by simulating static loads on the retaining wall from the soil backfill. Level‐ground centrifuge model results were used to select the parameters of the Pastor–Zienkiewicz mark III constitutive model used in the dynamic simulations of the soil. The effects due to different pore fluids were captured well by the simulations. The magnitudes of excess pore pressures in the soil, lateral thrust and its line of action on the wall, and wall bending strains, deflections, and accelerations were predicted well. Predictions of settlements and accelerations in the backfill were less satisfactory. Relatively high levels of Rayleigh damping were needed to be used in the retaining wall simulations in order to obtain numerically stable results, which is one of the shortcomings of the model. The procedure may be used for engineering purpose dealing with seismic analysis of flexible retaining walls where lateral pressures, bending strains and deflections in the wall are typically of importance. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

On reflection and diffraction due to a detached breakwater     

Wei-Po Huang  Chun-Ren Chou  John Z. Yim 《Ocean Engineering》2005,32(14-15):1762-1779

Wave reflection and diffraction due to the presence of a detached breakwater are studied with the aid of directional wave fields. At first, experiments were carried out for the case where a breakwater is the sole factor affecting the wave field. It is shown that, estimated directional spectra in front of a detached breakwater can be separated into two parts in the spatial domain. Denoting these as the incident and reflected part of the total energy, an estimate of the reflection coefficient can be obtained. An empirical equation is proposed. This equation relates the reflection coefficients with the distances of the measuring stations away from the breakwater, as well as directionality of the wave field. This equation was then applied to the experiments where the fishing harbour Ba-Do-Zhi (BDZ) was used as model. It is shown that favorable results are obtained. On the other hand, diffraction due to the detached breakwater was also studied in a similar way. It is shown that predictions based on the empirical equation are in quantitative agreements with measurements. It is proposed that these empirical equations can be used in engineering applications.  相似文献   

Nonlinear dynamics of a coupled surge-heave small-body ocean mooring system     

Oded Gottlieb  Solomon C.S. Yim 《Ocean Engineering》1997,24(5):479-495

An investigation of coupled surge-heave motion of a symmetric small-body ocean mooring system is carried out in this paper. The dynamical system, formulated using a Lagrangian approach in the vertical plane of motion, is characterized by a strong geometric mooring nonlinearity and includes a quadratic relative motion Morison form for the hydrodynamic damping. Numerical simulations reveal complex periodic and aperiodic solutions which include torus multiplying and chaotic motion. The onset of instabilities is discussed and a comparison with a limiting decoupled surge model is performed.  相似文献   

Young age bias of radiocarbon dates in pre-holocene marine deposits of Hong Kong and implications for Pleistocene stratigraphy   总被引：4，自引：0，他引：4  

W. W. -S. Yim  M. Ivanovich  K. -F. Yu 《Geo-Marine Letters》1990,10(3):165-172

Radiocarbon dates of pre-Holocene marine deposits in Hong Kong ranging from 21.580±1.210 to 45.700±2.000 years BP are found to be younger than uranium-series dates of mollusks and other indirect age evidence. Two mollusk samples yielded last interglacial ages of 130.500±5.300 and 142.000±20.000 years BP. respectively. Palynological and oxygen-isotope evidence shows that the marine deposits containing the mollusks were formed under marginally warmer temperature conditions than in the present day, which is consistent with a last interglacial age. Since old radiocarbon dates are likely to be minimum age estimates, similar studies carried out elsewhere would be of value to Pleistocene stratigraphy.  相似文献   

Nevelsk Earthquakes on Sakhalin Island on August 17, 2006 and August 2, 2007: the Results of a Field Macroseismic Survey of the Objects     

G. L. Koff  A. M. Ivanova  M. A. Kondrat’eva  I. V. Chesnokova  Kim Chun Un  Ten Su Mun  A. A. Malakhovskii 《Seismic Instruments》2010,46(4):325-340

The results of a survey of a number of objects in the field and towns of Nevelsk and Gornozavodsk, which were in the epicenter of an earthquake, are presented.  相似文献   

The November 15, 2006 Kuril Islands-Generated Tsunami in Crescent City, California     

L. Dengler  B. Uslu  A. Barberopoulou  S. C. Yim  A. Kelly 《Pure and Applied Geophysics》2009,166(1-2):37-53

On November 15, 2006, Crescent City in Del Norte County, California was hit by a tsunami generated by a M _w 8.3 earthquake in the central Kuril Islands. Strong currents that persisted over an eight-hour period damaged floating docks and several boats and caused an estimated $9.2 million in losses. Initial tsunami alert bulletins issued by the West Coast Alaska Tsunami Warning Center (WCATWC) in Palmer, Alaska were cancelled about three and a half hours after the earthquake, nearly five hours before the first surges reached Crescent City. The largest amplitude wave, 1.76-meter peak to trough, was the sixth cycle and arrived over two hours after the first wave. Strong currents estimated at over 10 knots, damaged or destroyed three docks and caused cracks in most of the remaining docks. As a result of the November 15 event, WCATWC changed the definition of Advisory from a region-wide alert bulletin meaning that a potential tsunami is 6 hours or further away to a localized alert that tsunami water heights may approach warning- level thresholds in specific, vulnerable locations like Crescent City. On January 13, 2007 a similar Kuril event occurred and hourly conferences between the warning center and regional weather forecasts were held with a considerable improvement in the flow of information to local coastal jurisdictions. The event highlighted the vulnerability of harbors from a relatively modest tsunami and underscored the need to improve public education regarding the duration of the tsunami hazards, improve dialog between tsunami warning centers and local jurisdictions, and better understand the currents produced by tsunamis in harbors.  相似文献   

Seasonal and spatial distribution of nonylphenol and IBP in Saemangeum Bay, Korea     

Li D  Dong M  Shim WJ  Hong SH  Oh JR  Yim UH  Jeung JH  Kanan N  Kim ES  Cho SR 《Marine pollution bulletin》2005,51(8-12):966-974

In order to investigate spatial and temporal distribution of organic pollutants in the Saemangeum Bay, organophosphorus pesticides (10), alkylphenols (8), chlorophenols (2), bisphenol A were analyzed from the surface seawater taken in 2002–2003. Most of the analytes were not detected in all stations except nonylphenol and S-benzyl-O,O-di-isopropyl phosphorothioate (IBP). Concentrations of nonylphenol and IBP ranged from ND to 298 ng/l and from ND to 1840 ng/l, respectively. The high levels of nonylphenol and IBP were found in the estuary areas of Mangyeong and Dongjin River. The levels of nonylphenol and IBP in surface seawater varied through seasons and the high levels of nonylphenol and IBP were in summer season (August). Based on real time monitoring of IBP and on correlation between concentrations of target compounds and contents of salinity in seawater, physical mixing and diffusion of seawater were found to be the major factors that affect the spatial distribution of IBP and nonylphenol in the Saemangeum Bay environment.  相似文献   

淡水珍珠新品种及加工工艺新进展     

徐翀  李立平  杨春 《地质科学译丛》2010,(1):50-54,I0002

目前,普通、低品质的淡水珍珠产品已无法满足大部分消费者的时尚需求,但随着珍珠养殖技术与加工技术的进一步发展,市场上出现了许多新的珍珠品种。系统地总结了目前中国珍珠市场上新造型的珍珠的特征,其中有核珍珠更适合于加工成各式各样的异形珠。以淡水无核珍珠为对象,重点探讨了刻面加工技术、镶嵌技术和雕刻技术在改善珍珠外观方面的应用,进一步分析了刻面珍珠的琢磨角度与时间;对椭圆形珍珠、腰线珍珠进行CZ镶嵌,使其外观得到了改善,提升了其价值。最后,对珍珠的雕刻技术进行了初步探讨。  相似文献   

Seismic response of rotating machines–structure–RFBI systems     

Wen‐Chyi Su  Alan G. Hernried  Solomon C. S. Yim 《地震工程与结构动力学》2000,29(2):213-240

The seismic response of a critical rotating machine either rigidly attached to a floor or independently isolated housed within an initially aseismically designed or uncontrolled structure are investigated. A particular isolation system, the Resilient‐Friction Base Isolator (RFBI), is employed. Finite element formulations of a rotor‐disk‐bearing model on a rigid base are developed. The equations of motion for the combined rotating machine–structure–RFBI systems are presented. Parametric studies are performed to investigate the effects of variations in system physical properties including friction coefficient, mass ratio, shaft flexibility, bearing rigidity, bearing damping and speed of rotation on the response of rotating machines for the combined rotating machine–structure–isolator systems. Comparative studies in the peak response of the rotating machine supported on various isolation systems and the corresponding fixed base system are carried out. The study indicates that the Resilient‐Friction Base Isolator can significantly reduce the seismic response of rotating components to potentially damaging ground excitations. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献