Contact detection algorithms for three-dimensional ellipsoids in discrete element modelling     

Xiaoshan Lin  Tang-Tat Ng 《国际地质力学数值与分析法杂志》1995,19(9):653-659

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Tsunami threat to the Pacific coast of Canada due to local earthquakes     

Max Ng  Paul H. Le Blond  Tad S. Murty 《Natural Hazards》1992,5(2):205-210

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Gamma emitters in Hong Kong water     

Shun-Yin Lau  Chung-Keung Man  Wai-Kwok Ng  Shui-Chun Au 《Environmental Geology》1990,16(2):129-131

Water samples, representing seawater, river water, reservoir water, drinking water, and underground water were studied through gamma-ray spectral analysis. Only gamma emitters in the²³⁸U and²³²Th series and⁴⁰K were detected. No fission product was detected with specific activity above 0.1 Bq/kg. The present data could be the baseline for future monitoring of the radioactivity released from a nuclear plant being built at a 50-km distance from Hong Kong. The variation of detected specific activities may be due to geological differences and the effect of plants.  相似文献   

Centrifuge modelling of the effects of root geometry on transpiration-induced suction and stability of vegetated slopes   总被引：1，自引：0，他引：1  

C. W. W. Ng  V. Kamchoom  A. K. Leung 《Landslides》2016,13(5):925-938

Shallow landslides (i.e. 1–2-m depth) on both man-made and natural slopes are of major concern worldwide that has led to huge amount of socio-economical losses. The use of vegetation has been considered as an environmentally friendly means of stabilising slopes. Existing studies have focused on the use of plant roots with different geometries to mechanically stabilise soil slopes, but there are little data available on the contribution of transpiration-induced suction to slope stability. This study was designed to quantify both the hydrological and mechanical effects of root geometry on the stability of shallow slopes. Centrifuge tests were conducted to measure soil suction in slope models supported by newly developed artificial roots. These artificial roots exhibit three different representative geometries (i.e. tap, heart and plate) and could simulate the effects of transpiration. The measured suction was then back-analysed through a series of finite element seepage-stability analyses to determine the factor of safety (FOS). It is revealed that after a rainfall event with a return period of 1000 years, the slope supported by heart-shaped roots retained the highest suction within the root depth, and thus, this type of root provided the greatest stabilisation effects. The FOS of the slope supported by the heart-shaped roots, through both mechanical reinforcement and transpiration-induced suction, is 16 and 28 % higher than that supported by the tap- and plate-shaped roots, respectively.  相似文献   

Characterization of a hypoxia-responsive leptin receptor (omLepR(L)) cDNA from the marine medaka (Oryzias melastigma)     

Wong MM  Yu RM  Ng PK  Law SH  Tsang AK  Kong RY 《Marine pollution bulletin》2007,54(6):797-803

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Chemical Zone of Nephrite in Alamas,Xinjiang, China     

Yan Liu  Jun Deng  Guanghai Shi  Taijin Lu  Huaiyu He  Yi-Nok Ng  Chonghui Shen  Liqiang Yang  Qingfei Wang 《Resource Geology》2010,60(3):249-259

The Hetian deposit, located south of the Tarim Basin in Xinjiang, China, is one of the world's largest dolomite-related nephrite deposits. In the Alamas orebody of the deposit, nephrite occurs as veins or lenses along faults or fissures of the adjacent dolomitic marble. Chemical analyses using electronic microscope probe analysis and X-ray fluorescence spectroscope were carried out on nephrite and dolomitic marble samples collected from a cross section in Alamas to investigate zonal structure of the orebody. The nephrite in Alamas is predominately composed of tremolite with minor calcite, titanite and phlogopite, and that dolomitic marble is relatively pure with a FeO content less than 0.20 wt. %. Contents of color-inducing elements, such as Fe, Mn, and Cr, increase gradually as color changes from white through white-green and then to green, resulting in the formation of color-distinctive zones. Tremolite grain size increases as color changes from white through white-green to green. The trend may be consistent with temperature changes from dolomitic marble to granodiorite, which, in turn, suggests that both change in color from white to green and variations of grain size with increasing temperature resulting in formation of the nephrite zonal structure. Both nephrite zonal structure and minor minerals, such as calcite, titanite and phlogopite found in the contact, indicate that this dolomite-related nephrite orebody is of a metasomatic origin under assumed pressure of 100–200 MPa and temperature <550°C.  相似文献   

Mount Everest, The Reconnaissance 1935: 'The Forgotten Adventure' - by Tony Astill     

Felix  Ng 《The Geographical journal》2006,172(4):351-351

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The gravitational field of a disk     

Fred T. Krogh  Edward W. Ng  William V. Snyder 《Celestial Mechanics and Dynamical Astronomy》1982,26(4):395-405

This note gives the gravitational potential of the disk {(x, y, z):x ² +y ² p ² , z=0} and the gravitational field at the point (x, y, z). Formulas for a ring can be obtained as the difference of our results for two different values ofp. Results are obtained in terms of elliptic integrals and we indicate how these functions can be computed efficiently. Formulas necessary for the computation of partial derivatives are also given.This paper presents the results of one phase of research carried out at the Jet Propulsion Laboratory, California Institute of Technology, under Contract NAS7-100, sponsored by the National Aeronautics and Space Administration.  相似文献   

A diatom model for inferring sea level change in the coastal waters of Hong Kong     

Sai L. Ng  Fung S. Sin 《Journal of Paleolimnology》2003,30(4):427-440

Diatoms were identified and enumerated from surface sediments of 25 sites in Double Haven, Hong Kong. The relationship between diatom species distribution and 14 environmental variables was examined using Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA). Water depth was identified as the most important environmental variable influencing the distribution of diatoms in Double Haven. Subsequently a Weighted Average (WA) calibration model was developed to infer water depth. The reliability of the model was evaluated by the error of prediction (RMSE_boot= 3.479) and the correlation (r ²= 0.7342) between observed and diatom-inferred values. This predictive calibration model has the potential to infer past sea level change in Hong Kong and the adjacent coastal areas.  相似文献   

Socio-spatial polarization and the (re-)distribution of deprived groups in world cities: A case study of Hong Kong     

Huiwei Chen  Mee Kam Ng  Murat Es  Joanna Lee  Winnie W. S. Mak  Yuying Tong 《Urban geography》2018,39(7):969-987

This paper draws on theoretical discussions of world cities to analyze socio-spatial polarization and (re-)distribution of deprived groups in Hong Kong in the 2000s. Intensifying global economic restructuring processes have induced socio-economic polarization, thereby producing deprived groups although the spatial outcomes may depend on the city-specific context. When local policies do not counteract the polarization trend, a spatial manifestation of widening socio-economic gaps can be expected. Intensified pro-growth policies adopted since Hong Kong’s return to Chinese rule in 1997 and during its economic recession in the early 2000s have worsened the impact of globalization-induced socio-economic and spatial restructuring. Census data from 2001 and 2011 show increasingly differentiated socio-economic profiles at the district level. The analysis offered in this study also points to a decreased socially mixed society in 2011 when the deprived groups lived in districts with less presence of the advantaged population.  相似文献