A Numerical Simulation on the Mesoscale Dynamics of the Spring Bloom in the Sea of Japan     

Tetsuo Yanagi  Goh Onitsuka  Naoki Hirose  John-Hwan Yoon 《Journal of Oceanography》2001,57(6):617-630

The northward migration of spring bloom was observed in the Sea of Japan from April to May 1997 by the Ocean Color and Temperature Scanner (OCTS) on board the Advanced Earth Observing Satellite (ADEOS). This phenomenon is well simulated with a numerical ecosystem model coupled with a hydrodynamic model. The hydrodynamic model is the Geophysical Fluid Dynamics Laboratory (GFDL) Modular Ocean Model (MOM). The ecosystem model consists of five components: dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), phytoplankton, zooplankton and detritus. Results of the numerical ecosystem model suggest that the mesoscale development of the spring bloom in the Sea of Japan is related to that of sea water temperature, and that the bloom is limited by the depletion of DIN. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Torsional response of nonductile structures with soft‐first‐storey          下载免费PDF全文

Key Seng Goh  Tso‐Chien Pan 《地震工程与结构动力学》2015,44(1):1-21

In this paper, torsional response of nonductile structures with soft‐first‐storey subjected to bidirectional ground motions is studied using a simplified two‐storey model with two‐way eccentricities. The stiffness ratio of second storey to first storey is varied to create different levels of soft‐first‐storey effect, while the stiffness eccentricity is varied to create torsional effects. Different overstrength ratios are used in the simplified models to study the response of structure with different structural capacity. Hysteretic model with strength deterioration and stiffness degradation properties is used to capture the deterioration of element stiffness and strength. Ductility capacity of 2.0 is used as the models are for nonductile structures. In general, displacement amplification of irregular model with respect to regular model increases as stiffness ratio increases, while no consistent trend of changes in displacement amplification is found with increase in stiffness eccentricity. It is found that the displacement amplification due to only soft‐first‐storey effect can be conservatively taken as 1.5. Coupling of torsional and soft‐first‐storey effects is more significant in affecting the displacement amplification of elements at flexible side. The trend of changes in displacement amplification of elastic system is similar to that of inelastic system. The displacement amplification of elements at the flexible side is larger than that at the stiff side. The elements at the flexible side in the direction of shorter uncoupled lateral period have larger displacement response than those in the orthogonal direction. Ductility demand–capacity curves subsequently constructed can be used to approximately assess the seismic performance of existing structures and as guidelines for designing structures in Singapore to withstand the maximum credible earthquake considering the coupling of torsional and soft‐first‐storey effects. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Establishing the thermal threshold of the tropical mussel Perna viridis in the face of global warming     

B.P.L. Goh  C.H. Lai 《Marine pollution bulletin》2014

With increasing recognition that maximum oxygen demand is the unifying limit in tolerance, the first line of thermal sensitivity is, as a corollary, due to capacity limitations at a high level of organisational complexity before individual, molecular or membrane functions become disturbed. In this study the tropical mussel Perna viridis were subjected to temperature change of 0.4 °C per hour from ambient to 8–36 °C. By comparing thermal mortality against biochemical indices (hsp70, gluthathione), physiological indices (glycogen, FRAP, NRRT) and behavioural indices (clearance rate), a hierarchy of thermal tolerance was therein elucidated, ranging from systemic to cellular to molecular levels. Generally, while biochemical indices indicated a stress signal much earlier than the more integrated behavioural indices, failure of the latter (indicating a tolerance limit and transition to pejus state) occurred much earlier than the other indices tending towards thermal extremities at both ends of the thermal spectrum.  相似文献   

Assessment of basal stability for braced excavation systems using the finite element method     

A. T. C. Goh 《Computers and Geotechnics》1990,10(4):325-338

Conventional methods of predicting the basal stability of braced excavations are unable to take into consideration the stiffness of the retaining wall and the depth of penetration of the wall below the bottom of the excavation. A simple and improved procedure for predicting the stability of strutted excavations using the finite element method is presented. Detailed studies were carried out to assess the effects of the wall properties and soil geometry on the stability of the excavation.  相似文献   

Benchmarks for validating range-dependent seismo-acousticpropagation codes     

Joo Thiam Goh Schmidt  H. Gerstoft  P. Woojae Seone 《Oceanic Engineering, IEEE Journal of》1997,22(2):226-236

The availability of fast and relatively low-cost computing power has resulted in radical changes to the role of seismo-acoustic modeling. With the increase in the number of models available, there is the inevitable question of how can one go about validating all these numerical schemes. Recently, the issue of establishing reference solutions for range dependent ocean acoustic problems was addressed within the Acoustical Society of America. This has resulted in a set of well-defined benchmarks for range-dependent fluid problems. However, to date, there is no consistent set of benchmarks for the range-dependent seismo-acoustic codes. In this paper, we present a collection of problems intended for general use by the modeling community for validation of new computational schemes. A number of new seismo-acoustic codes are applied to produce reference solutions for these benchmarks  相似文献   

Sulfur electronic environments in α-NiS and β-NiS: examination of the relationship between coordination number and core electron binding energies     

Siew Wei Goh  Alan N. Buckley  Robert N. Lamb  William M. Skinner  Allan Pring  Haipeng Wang  Liang-Jen Fan  Ling-Yun Jang  Lee-Jene Lai  Yaw-wen Yang 《Physics and Chemistry of Minerals》2006,33(2):98-105

X-ray photoelectron spectra have been obtained under the same experimental conditions for synthetic α-NiS and natural β-NiS in order to establish any difference in S electronic environment, and to test the proposition that S core electron binding energies increase measurably with coordination number when the same metal is in different sulfide structures or lattice sites. The Ni and S electronic environments in the two NiS structures have been further probed by near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and the NEXAFS spectra interpreted by reference to spectra simulated by ab initio calculations. The photoelectron and NEXAFS spectra for freshly prepared surfaces of α-NiS and β-NiS were found to be similar, with only subtle differences in electronic environment evident in the experimental and simulated NEXAFS spectra. The measured and calculated core electron binding energies did not support the previously postulated relationship between S coordination number and electron binding energies.  相似文献   

Pentlandite sulfur core electron binding energies     

Siew Wei Goh  Alan N. Buckley  Robert N. Lamb  Liang-Jen Fan  Ling-Yun Jang  Yaw-wen Yang 《Physics and Chemistry of Minerals》2006,33(7):445-456

A number of freshly abraded surfaces of pentlandite have been characterised by X-ray photoelectron spectroscopy to establish whether the initial intensity of the S 2p component near 161.4 eV, previously assigned to the 25% of S atoms in fourfold coordination by metal atoms in pentlandite, was always at least 25% of the total S 2p intensity. It was found that the intensity of this S 2p component could be lower than 20% for surfaces that were not significantly oxidised. To assess whether the proposed 0.75–0.8 eV 2p binding energy difference for the two sulfur environments in pentlandite was justified, ab initio calculations of the difference in core electron binding energies and of the densities of unfilled states have been carried out. The corresponding simulated S K near-edge X-ray absorption fine structure (NEXAFS) spectra have been compared with experimental spectra. The calculated S 2p and S 1s binding energy differences were 0.45 and 0.5 eV at most, in agreement with the experimental NEXAFS spectra. It was concluded that the S 2p component near 161.4 eV arises entirely from violarite present at the pentlandite surface rather than from 4-coordinate S in pentlandite itself. Ab initio calculations of the difference in S 2p binding energies for the 2- and 3-coordinate S in stibnite have also been carried out and found to be quite small, in agreement with previously reported experimental values. Nevertheless, for both pentlandite and stibnite, calculations have confirmed that an increase in coordination number is associated with an increase in sulfur core electron binding energies, even although that increase is barely measurable for the latter sulfide.  相似文献   

Estimation of diaphragm wall deflections for deep braced excavation in anisotropic clays using ensemble learning     

Runhong Zhang  Chongzhi Wu  Anthony T.C.Goh  Thomas Bohlke  Wengang Zhang 《地学前缘(英文版)》2021,12(1):365-373

This paper adopts the NGI-ADP soil model to carry out finite element analysis,based on which the effects of soft clay anisotropy on the diaphragm wall deflections in the braced excavation were evaluated.More than one thousand finite element cases were numerically analyzed,followed by extensive parametric studies.Surrogate models were developed via ensemble learning methods(ELMs),including the e Xtreme Gradient Boosting(XGBoost),and Random Forest Regression(RFR)to predict the maximum lateral wall deformation(δhmax).Then the results of ELMs were compared with conventional soft computing methods such as Decision Tree Regression(DTR),Multilayer Perceptron Regression(MLPR),and Multivariate Adaptive Regression Splines(MARS).This study presents a cutting-edge application of ensemble learning in geotechnical engineering and a reasonable methodology that allows engineers to determine the wall deflection in a fast,alternative way.  相似文献