Multivariate Adaptive Regression Splines Application for Multivariate Geotechnical Problems with Big Data     

Wengang Zhang  Anthony T. C. Goh  Yanmei Zhang 《Geotechnical and Geological Engineering》2016,34(1):193-204

Despite the rapid increases in processing speed and memory of low-cost computers, the enormous computational costs of running complicated numerical analyses such as finite element simulations makes it impractical to rely exclusively on simulation for the purpose of design optimization since many geotechnical problems are highly nonlinear and multivariate. To reduce the cost, surrogate models, also known as meta-models, are constructed and then used in place of the actual numerical simulation models. To ensure the surrogate model is more reliable, the ranges of the design variables should be as wide as possible. Thus meta-modeling techniques capable of analyzing multivariate problems are desirable. This paper explores the use of a fairly simple nonparametric regression procedure known as multivariate adaptive regression splines (MARS) in approximating the relationship between the inputs and outputs with a big data. First the basis of the MARS methodology and its associated procedures are explained in detail. Then two complicated geotechnical problems are presented to demonstrate the function approximating capabilities of MARS and its efficiency in dealing with multivariate problems involving large amounts of data. This paper demonstrates that the MARS algorithm is capable of producing simple, accurate and easy-to-interpret models and estimating the contributions of the input variables.  相似文献   

Climate extremes: an observation and projection of its impacts on food production in ASEAN     

Jonatan A. Lassa  Allen Yu-Hung Lai  Tian Goh 《Natural Hazards》2016,80(1):19-22

Climate change alters global food systems, especially agriculture and fisheries—significant aspects of the livelihoods and food security of populations. The 2014 IPCC Fifth Assessment Report identified Southeast Asia as the most vulnerable coastal region in the world, and highlighted the potential distribution of impacts and risks of climate change in the region. While climate hazards may differ across geographical regions, the impact of climate extremes on food production will affect marginal farmers, fishers and poor urban consumers disproportionately, as they have limited capacities to adapt to and recover from extreme weather events. Governments and other stakeholders need to respond to climate extremes and incorporate adaptation into national development plans. Unfortunately, there is still limited peer-review publication on the subject matter. This paper presents some findings from research on observed and projected loss and damage inflicted by climate extremes on agricultural crops in Southeast Asia.  相似文献   

Anoma Pieris,Hidden Hands and Divided Landscapes: A Penal History of Singapore's Plural Society     

Daniel P.S. Goh 《Singapore journal of tropical geography》2010,31(3):404-406

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An X-ray photoelectron and absorption spectroscopic investigation of the electronic structure of cubanite, CuFe2S3     

Siew Wei Goh  Alan N. Buckley  William M. Skinner  Liang-Jen Fan 《Physics and Chemistry of Minerals》2010,37(6):389-405

X-ray photoelectron and absorption spectra have been obtained for natural specimens of cubanite and compared with the corresponding spectra for chalcopyrite. Synchrotron X-ray photoelectron spectra of surfaces prepared by fracture under ultra-high vacuum revealed some clear differences for the two minerals, most notably those reflecting their different structures. In particular, the concentration of the low binding energy S species formed at cubanite fracture surfaces was approximately double that produced at chalcopyrite surfaces. However, the core electron binding energies for the two S environments in cubanite were not significantly different, and were similar to the corresponding values for the single environment in chalcopyrite. High binding energy features in the S 2p and Cu 2p spectra were not related to surface species produced either by the fracture or by oxidation, and most probably arose from energy loss due to inter-band excitation. Differences relating to the Fe electronic environments were detectable, but were smaller than expected from some of the observed physical properties and Mössbauer spectroscopic parameters for the two minerals. X-ray absorption and photoelectron spectra together with the calculated densities of states for cubanite confirmed an oxidation state of Cu^I in the mineral. It was concluded that the best formal oxidation state representation for cubanite is Cu^I(Fe₂)^VS ₃ ^?II .  相似文献   

Three‐dimensional finite element analyses of passive pile behaviour     

L. F. Miao  A. T. C. Goh  K. S. Wong  C. I. Teh 《国际地质力学数值与分析法杂志》2006,30(7):599-613

Piles may be subjected to lateral soil pressures as a result of lateral soil movements from nearby construction‐related activities such as embankment construction or excavation operations. Three‐dimensional finite element analyses have been carried out to investigate the response of a single pile when subjected to lateral soil movements. The pile and the soil were modelled using 20‐node quadrilateral brick elements with reduced integration. For compatibility between the soil–pile interface elements, 27‐node quadrilateral brick elements with reduced integration were used to model the soil around the pile adjacent to the soil–pile interface. A Mohr–Coulomb elastic–plastic constitutive model with large‐strain mode was assumed for the soil. The analyses indicate that the behaviour of the pile was significantly influenced by the pile flexibility, the magnitude of soil movement, the pile head boundary conditions, the shape of the soil movement profile and the thickness of the moving soil mass. Reasonable agreement is found between some existing published solutions and those developed herein. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Optimal tonal detectors based on the power spectrum     

Chun Ru Wan Joo Thiam Goh Hong Tat Chee 《Oceanic Engineering, IEEE Journal of》2000,25(4):540-552

The detection of tonals embedded in noise is an important sonar function and the traditional power spectrum analysis method has been widely used for this purpose. Wagstaff et al. (1997) proposed the WISPR (Wagstaff's Integration Silencing PRocessor) family processors, which perform a nonlinear integration or combination of the power spectrum observations. In this paper, we analyze the statistical property of the power spectrum observations and develop novel tonal detectors by optimally integrating the spectrum observations. The optimal detectors are derived by using the method of maximum likelihood hypothesis test. The results from simulations and real sea trial data have shown that the proposed detectors are promising in detecting tonals  相似文献   

Empirical relationships between natural vibration period and height of buildings in Singapore          下载免费PDF全文

Tso‐Chien Pan  Key Seng Goh  Kusnowidjaja Megawati 《地震工程与结构动力学》2014,43(3):449-465

Singapore is a classic case of a modern metropolis with low hazard but high exposure to the seismicity in Sumatra. Because of land shortage, more than 80% of the population lives in high‐rise residential buildings. As part of the efforts to assess the seismic performance of buildings in Singapore subjected to long‐distance Sumatran earthquakes, relationships between the natural vibration period and height of high‐rise public residential buildings in Singapore are derived empirically by conducting ambient vibration tests on 116 buildings. The measured buildings have a height ranging from 4 to 30 stories. The aspect ratio of buildings in plan is found to be insignificant in affecting the natural vibration period of the first mode of the buildings. The period‐height relationships are derived using regression analysis considering the site properties of a building. It is concluded that the vibration periods estimated from the proposed period‐height relationship for buildings located at soft‐soil site are about 40% longer than the vibration periods estimated for buildings located at firm‐soil site. Measurements are also conducted to study the influence of buildings on the measured frequency of the surrounding soil. For this purpose, two buildings with 25 and 30 stories located at firm‐soil site and soft‐soil site, respectively, are selected. It is found that the distance of building influence on the measured frequency of the surrounding soil may reach up to one building height for a firm‐soil site and two building heights for a soft‐soil site. Additional data of natural vibration periods of 19 instrumented residential buildings, which have height ranging from 9 to 30 stories, were obtained from the building response recorded during the September 30, 2009 Sumatran earthquake event. The natural vibration periods of these buildings are compared with those estimated using the proposed period‐height relationships, and the absolute differences are found to be less than 12%. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Monitoring of DSP toxins in small-sized plankton fraction of seawater collected in Mutsu Bay,Japan, by ELISA method: relation with toxin contamination of scallop     

Imai I  Sugioka H  Nishitani G  Mitsuya T  Hamano Y 《Marine pollution bulletin》2003,47(1-6):114-117

Monitorings were conducted on DSP toxins in mid-gut gland of scallop (mouse assay), cell numbers of toxic dinoflagellate species of Dinophysis, and diarrhetic shellfish poisoning (DSP) toxins in small-sized (0.7-5 microm) plankton fraction of seawater collected from surface (0 m) and 20 m depth at a station in Mutsu Bay, Aomori Prefecture, Japan, in 2000. A specific enzyme-linked immunosorbent assay (ELISA) was employed for the analysis of DSP toxins in small-sized plankton fraction using a mouse monoclonal anti-okadaic acid antibody which recognizes okadaic acid, dinophysistoxin-1, and dinophysistoxin-3. DSP toxins were detected twice in the mid-gut gland of scallops at 1.1-2.3 MU (mouse units) g(-1) on 26 June and at 0.6-1.2 MU g(-1) on 3 July, respectively. Relatively high cell densities of D. fortii were observed on 26 June and 11 September, and may only contribute to the bivalve toxicity during late June to early July. D. acuminata did not appear to be responsible for the toxicity of scallops in Mutsu Bay in 2000. ELISA monitoring of small-sized plankton fraction in seawater could detect DSP toxins two weeks before the detection of the toxin in scallops, and could do so two weeks after the loss of the bivalve toxicity by mouse assay. On 17 July, toxic D. fortii was detected at only small number, <10 cells l(-1), but DSP toxins were detected by the ELISA assay, suggesting a presence of other toxic small-sized plankton in seawater. For the purpose of reducing negative impacts of DSP occurrences, monitorings have been carried out hitherto on DSP toxins of bivalve tissues by mouse assay and on cell densities of "toxic" species of Dinophysis. Here we propose a usefulness of ELISA monitoring of plankton toxicity, especially in small-sized fraction, which are possible foods of mixotrophic Dinophysis, as a practical tool for detecting and predicting DSPs in coastal areas of fisheries grounds of bivalve aquaculture.  相似文献   

Hydraulic conductivity and pore fluid chemistry in artificially weathered plastic clay   总被引：1，自引：0，他引：1  

J. Graham  K. Yuen  T. B. Goh  P. Janzen  V. Sivakumar 《Engineering Geology》2001,60(1-4):69-81

Triaxial and oedometer tests have examined how freezing–thawing (FT) and drying–wetting (DW) affect the hydraulic conductivity of a natural plastic clay. Because the clay was expansive, FT and DW in the laboratory produced only one order of magnitude increase in hydraulic conductivity above the ‘undisturbed’ value when permeated with water. Permeation with sodium carbonate or dimethyl sulfoxide reduced the hydraulic conductivity towards the undisturbed value, though some increases still remained. Hydraulic conductivities measured by oedometer were lower than those in the triaxial tests and varied strongly with applied pressure.  相似文献   

Comment on the paper: “[1H] and [13C]NMR studies on the importance of aromatic structures in fulvic and humic acids” (Ruggieroet al., 1979)     

M.A. Wilson  K.M. Goh 《Geochimica et cosmochimica acta》1981,45(3):489-490

Some statements referring to our work on ¹³C NMR of humic and fulvic acids have been recently reported in this journal by Ruggiero and co-workers. They are discussed in order to avoid possible misinterpretations.  相似文献