A study on one-dimensional consolidation of layered systems     

P. K. K. Lee  K. H. Xie  Y. K. Cheung 《国际地质力学数值与分析法杂志》1992,16(11):815-831

A general analytical solution, which is more explicit than the one given by Schiffman and Stein,¹ for the problem of one-dimensional consolidation of layered soils is presented. A relevant computer program is developed and the computed results on some examples are included. From these results, an in-depth study on the one-dimensional consolidation behaviour of layered systems is then made. It is demonstrated through these examples that both the solution technique and the computer program developed are very efficient. It is found that the effects of coefficients of permeability and volume compressibility of soil on the consolidation of layered systems are different and cannot be embodied into the coefficient of consolidation of soil. The stiffness of soil layer also plays an important role on the rate of consolidation.  相似文献   

Effects of dietary vitamin C on the immune function of shrimps, Penaeus chinensis     

Wang Weiqing  Li Aijie  Cheung Siugin 《中国海洋大学学报(英文版)》2002,1(1):50-54

Prepared in this experiment were six groups of diets, i.e. VC0, VC1, VC2, VC3, VC4 and VC5 with the contents of vitamin C (VCmg(100 g)⁻¹ diet) of 0, 100, 200, 400, 800, and 1200 respectively. It was found that vitamin C increased the concentrations of immunoglobulin-like (IgG-like, IgA-like and IgM-like) substances in the serum of Penaeus chinensis after a feeding period of 3 weeks. The differences among groups were significant (P<0.01), but there was no difference in the contents of complement3-like and complement4-like substances in the serum (P>0.05). Phenoloxidase (PO) activity in the serum of VC3 group shrimps was higher than that of VC0 and other groups, but no significant difference was observed between VC0 group and other groups. Furthermore, bactericidal activity of the serum to Vibrio parahaemolyticus in shrimps fed with the VC1 diet was higher than that in the other groups (P<0.01), while no difference was demonstrated among all groups for the bactericidal activity to Vibrio alginolyticus (P>0.05). It is, therefore, suggested that vitamin C (100–400 mg(100 g)⁻¹ diets) could be used as an immunostimulant of P. chinensis.  相似文献   

Size effects of suspended particles on gill damage in green-lipped mussel Perna viridis   总被引：1，自引：0，他引：1  

Cheung SG  Shin PK 《Marine pollution bulletin》2005,51(8-12):801-810

The green-lipped mussels Perna viridis were exposed to <500 μm suspended solids (SS) with concentrations of 0 (control), 250, 500, 750 and 1000 mg/L for 14 days, followed by transferring to clean, filtered seawater for 28 days. Results of scanning microscopy showed significantly higher damages to the cilia on the frontal surface of the gill filaments than that on the abfrontal surface in both demibranchs. Percent ciliary depletion varied with SS concentrations and time. No sign of recovery of the gill filaments was observed after the mussels were transferred to clean seawater. In a second experiment, mussels were exposed to SS with size range from <63, >125–<250 and >250–<500 μm at 600 mg/L, together with a control (0 mg/L) for 14 days, followed by transferring to clean, filtered seawater for 28 days. Results of scanning microscopy showed significant ciliary damages in both the ascending and descending lamellae under the three particle size groups as compared with the control. Percent depletion of frontal cilia was most serious for the >250–<500 μm size group and least for the <63 μm size group. However, percent depletion of abfrontal cilia was most serious for the >125–<250 μm size group and least for the <63 μm size group. No recovery of ciliary damages was observed. The effects of particle size of suspended sediments on the morphological damages of gill filaments in the green-lipped mussels were discussed.  相似文献   

Potential impact of reforestation programmes and uncertainties in land cover effects over the loess plateau: a regional climate modeling study     

Lang Wang  Kevin K. W. Cheung 《Climatic change》2017,144(3):475-490

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Regulation of Tilapia metallothionein gene expression by heavy metal ions     

Andrew P. L. Cheung  Timothy H. -J. Lam  King Ming Chan   《Marine environmental research》2004,58(2-5):389

Tilapia is a common fish species inhabiting inland waters and estuarine regions in Hong Kong and Southeast Asia, and useful for bio-monitoring of metal pollution. Metallothionein (MT) gene expression in fish tissues has been useful to sub-lethal risk assessment as biomarker of exposure to metal ions in fishes inhabiting metal contaminated area. To investigate metal inductions of Tilapia MT gene expression in vivo, Tilapias were injected with different concentrations of heavy metals and tissues were then removed for quantitative PCR assay using mimic PCR methods. All of the metal ions tested (Cu²⁺, Cd²⁺, Hg²⁺, Ni²⁺, Pb²⁺ and Zn²⁺) were able to induce hepatic MT mRNA levels. Renal MT mRNA levels of Cd²⁺ and Zn²⁺ treated fish was not induced with significant fold induction, however MT mRNA levels in gills were sensitive to the administrations of these metal ions. These data indicated that Tilapia MT mRNA levels in gills and liver are sensitive biomarker of exposure to various metal ions.  相似文献   

Modeling of storm-induced coastal flooding for emergency management   总被引：3，自引：0，他引：3  

K. F. Cheung  A. C. Phadke  Y. Wei  R. Rojas  Y. J. -M. Douyere  C. D. Martino  S. H. Houston  P. L. -F. Liu  P. J. Lynett  N. Dodd  S. Liao  E. Nakazaki 《Ocean Engineering》2003,30(11):1353-1386

This paper describes a model package that simulates coastal flooding resulting from storm surge and waves generated by tropical cyclones. The package consists of four component models implemented at three levels of nested geographic regions, namely, ocean, coastal, and nearshore. The operation is automated through a preprocessor that prepares the computational grids and input atmospheric conditions and manages the data transfer between components. The third generation spectral wave model WAM and a nonlinear long-wave model calculate respectively the wave conditions and storm surge over the ocean region. The simulation results define the water levels and boundary conditions for the model SWAN to transform the storm waves in coastal regions. The storm surge and local tides define the water level in each nearshore region, where a Boussinesq model uses the wave spectra output from SWAN to simulate the surf-zone processes and runup along the coastline. The package is applied to hindcast the coastal flooding caused by Hurricanes Iwa and Iniki, which hit the Hawaiian Island of Kauai in 1982 and 1992, respectively. The model results indicate good agreement with the storm-water levels and overwash debris lines recorded during and after the events, demonstrating the capability of the model package as a forecast tool for emergency management.  相似文献   

Coalbed methane producibility from the Mannville coals in Alberta, Canada: A comparison of two areas   总被引：2，自引：1，他引：1  

T. Gentzis  F. Goodarzi  F.K. Cheung  F. Laggoun-Dfarge 《International Journal of Coal Geology》2008,74(3-4):237-249

Selenium concentrations were measured in five rock cores from a mine in Boone County, West Virginia to determine their relationship to sulfur, rock type and stratigraphic location. The samples spanned the Winifrede and Coalburg coal beds of the Middle Pennsylvania upper Kanawha Formation and included coals and clastic lithologies. The coals generally contained the highest concentrations of Se and the sandstones the lowest. No correlation was observed between total Se and sulfur concentrations for either the entire data set or for individual lithologies. Better correlations were identified for log concentrations between total Se and total organic carbon. Principal component analysis identified a strong sulfur–acid component, interpreted to be due to sulfide mineral presence, which correlates well with S but not with Se. Coal sample chemistry is more likely to load onto this component while clastic rock chemistry is more likely to load onto the second, non-sulfur component. Se concentrations load onto both components indicating they are not controlled by a single overriding chemistry. Selective extractions indicate that Se is distributed between both sulfide and organically-bound fractions, as defined by the test. Overall, the lack of correlation between Se and S, the distribution of Se among extracted fractions, and the loading of Se onto both sulfur and non-sulfur components support that the Se in these rock layers is distributed in more than one chemically-bound form. Non-coal rock units with the highest concentrations of Se were found adjacent to coal beds, suggesting that redistribution of Se may have occurred post-deposition. The acidic domed swamps that formed these coals were low in sulfur and a reasonable chemical setting to accumulate Se if it were introduced. The preservation of Se in the domed swamp peat coupled with post-depositional redistribution may partly explain the data presented.  相似文献   

Energetics and dynamics associated with two typical mobile trough pathways over East Asia in boreal winter     

Marco Yu-Ting Leung  Hoffman Ho-Nam Cheung  Wen Zhou 《Climate Dynamics》2015,44(5-6):1611-1626

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Major ion and isotope geochemistry of fluids and gases from coalbed methane and shallow groundwater wells in Alberta,Canada     

Katrina Cheung  Patrick Klassen  Bernhard Mayer  Fariborz Goodarzi  Ramon Aravena 《Applied Geochemistry》2010

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Effects of nitrogen and sulphide on macroinfaunal community: a microcosm study     

Shin PK  Cheung CK  Cheung SG 《Marine pollution bulletin》2006,52(11):1333-1339

A microcosm experiment was conducted to test the short-term effects of nitrogen (as TKN, total Kjeldahl nitrogen) and sulphide (as AVS, acid volatile sulphide) on macrobenthic infauna over a period of 8 weeks. The experiment consisted of four treatments using sediment cores (D: 8 cm, H: 20 cm) with addition of: I, nitrogen (N) to an in situ mean level of 0.48 mg Ng(-1) dw; II, sulphidic solution (S) to an in situ mean level of 318.8 microM S g(-1) dw; III, nitrogen and sulphidic solution (NS) to in situ mean levels of 0.45 mg Ng(-1) dw and 329.0 microM S g(-1) dw, respectively, and IV, control with no addition of N and S. Sediment cores were retrieved for analysis of infaunal composition after weeks 2, 4 and 8. A total of 646 specimens of macrobenthic infauna belonging to 27 species were recorded from the cores, in which polychaetes were the most abundant with respect to species and individual numbers. Mean species number and diversity H' of the control and N treatment was statistically higher than S and NS treatments, mean individual number of the S treatment was larger than the NS treatment, and mean evenness J of the S treatment was lower than the N and NS treatments as well as the control. Individual numbers also showed a significant increase from weeks 2 to 8, whereas evenness J decreased in weeks 4 and 8. Multivariate analyses of the faunal data suggested that benthic composition of the N treatment and control did not differ during the experimental period, but changes in benthic structure in S and NS treatments were evident. The present findings demonstrated the dose-response relationship of benthic species changes under controlled addition of N and S. The response to N and S additions in the sediment microcosms was in agreement with the general effects of organic enrichment on macrobenthic communities along a spatial gradient of organic pollution as described by Pearson and Rosenberg [Pearson, T.H., Rosenberg, R., 1978. Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanography and Marine Biology Annual Review 16, 229-311]. However, in the present experiment, community changes in the treatments were observable in a short, temporal scale.  相似文献