Different Lithological Varieties of Bukit Timah Granite in Singapore: a Preliminary Comparison Study on Engineering Properties     

Louis Ngai Yuen Wong  Varun Maruvanchery 《Rock Mechanics and Rock Engineering》2016,49(7):2923-2935

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Ubiquitous interactive visualization of 3D mantle convection using a web-portal with Java and Ajax framework     

James B. S. G. Greensky  Wojciech Walter Czech  David A. Yuen  Michael Richard Knox  Megan Rose Damon  Shi Steve Chen  M. Charley Kameyama 《Visual Geosciences》2008,13(1):105-115

We have developed a new strategy and espouse a novel paradigm for large-scale computing and real-time interactive visualization. This philosophy calls for intense interactive sessions for a couple of hours at a time at the expense of storing data on many disk drives during regular or heroic runs on massively parallel systems. We have already carried out successfully real-time volume-rendering visualization by employing hundreds of processors for a grid with over 25 million unknowns. Both Cartesian and spherical 3D mantle convection are visualized. The volume-rendered images are viewed on a large display device, with many panels holding around 13 million pixels. We will employ a software strategy involving an hierarchical rendering service, which will have as software an Ajax interface for interactive visualization of large data sets on many different platforms from desktop PC’s to hand-held devices, such as the OQO and the Nokia N-800. An option for stereo viewing is also implemented. We have installed a user interface as web application, using Java and Ajax framework in order to achieve over the Internet reasonable accessibility to our ongoing runs. Our goal is to expand the array of interactive devices, which will make it feasible to carry out ubiquitous visualization and monitoring of large-scale simulations or onsite events and to allow for collaborations across oceans.  相似文献   

Experiments in scientific computation on the PlayStation 3     

Erik O. D. Sevre  Monica D. Christiansen  Matt Broten  Shuo M. Wang  David A. Yuen 《Visual Geosciences》2008,13(1):125-132

The Sony PlayStation 3 (PS3) offers the computational power of a parallel processor at low cost, which makes it a great starter unit for development in parallel programming. To explore the capabilities of the unit, we took a simple ray tracing program and extended it to render triangulated height field data across the PS3’s 6 synergistic processing units (SPUs). We also implemented the heat averaging equation as a precursor to CFD analysis on the PS3. In our studies, we found the Cell engine in the PS3 to be a powerful machine, however great care must be taken while developing because its unique platform calls for many levels of optimization to ensure efficiency. For insight on early work done on modern stream computing and GPU processing look up the Merrimac project and Pat Hanrahan.  相似文献   

Visualization of tsunami waves with Amira package     

Erik O. D. Sevre  Dave A. Yuen  Yingchun Liu 《Visual Geosciences》2008,13(1):85-96

In recent years numerical investigations of tsunami wave propagation have been spurred by the magnitude 9.3 earthquake along the Andaman–Sumatra fault in December, 2004. Visualization of tsunami waves being modeled can yield a much better physical understanding about the manner of wave propagation over realistic seafloor bathymetries. In this paper we will review the basic physics of tsunami wave propagation and illustrate how these waves can be visualized with the Amira visualization package. We have employed both the linear and nonlinear versions of the shallow-water wave equation. We will give various examples illustrating how the files can be loaded by Amira, how the wave-heights of the tsunami waves can be portrayed and viewed with illumination from light sources and how movies can be used to facilitate physical understanding and give important information in the initial stages of wave generation from interaction with the ambient geological surroundings. We will show examples of tsunami waves being modeled in the South China Sea, Yellow Sea and southwest Pacific Ocean near the Solomon Islands. Visualization should be a part of any training program for teaching the public about the potential danger arising from tsunami waves. We propose that interactive visualization with a web-portal would be useful for understanding more complex tsunami wave behavior from solving the 3-D Navier–Stokes equation in the near field.  相似文献   

Differential developmental toxicity of naphthoic acid isomers in medaka (Oryzias latipes) embryos     

Carney MW  Erwin K  Hardman R  Yuen B  Volz DC  Hinton DE  Kullman SW 《Marine pollution bulletin》2008,57(6-12):255-266

Polycyclic aromatic hydrocarbons (PAHs) are widespread persistent pollutants that readily undergo biotic and abiotic conversion to numerous transformation products in rivers, lakes and estuarine sediments. Here we characterize the developmental toxicity of four PAH transformation products each structural isomers of hydroxynaphthoic acid: 1H2NA, 2H1NA, 2H3NA, and 6H2NA. Medaka fish (Oryzias latipes) embryos and eleutheroembryos were used to determine toxicity. A 96-well micro-plate format was used to establish a robust, statistically significant platform for assessment of early life stages. Individual naphthoic acid isomers demonstrated a rank order of toxicity with 1H2NA>2H1NA>2H3NA>6H2NA being more toxic. Abnormalities of circulatory system were most pronounced including pericardial edema and tube heart. To determine if HNA isomers were AhR ligands, spatial-temporal expression and activity of CYP1A was measured via in vivo EROD assessments. qPCR measurement of CYP1A induction proved different between isomers dosed at respective concentrations affecting 50% of exposed individuals (EC50s). In vitro, all ANH isomers transactivated mouse AhR using a medaka CYP1A promoter specific reporter assay. Circulatory abnormalities followed P450 induction and response was consistent with PAH toxicity. A 96-well micro-plates proved suitable as exposure chambers and provided statistically sound evaluations as well as efficient toxicity screens. Our results demonstrate the use of medaka embryos for toxicity analysis thereby achieving REACH objectives for the reduction of adult animal testing in toxicity evaluations.  相似文献   

Visualization and Analysis of Mixing Dynamical Properties in Convecting Systems with Different Rheologies     

A. A. Ten  D. A. Yuen  Yu. Yu. Podladchikov 《Visual Geosciences》1999,4(1):1-15

We analyzed and compared the mixing properties of 2-D mantle convection models. Two rheologically different models, Newtonian and non-Newtonian (power-law), were considered with both the line and field methods. The line method is based on monitoring of passive particles joined into lines, while the field method relies on the advection of a passive scalar field. Both visual and quantitative estimates revealed that the efficiency of the Newtonian mixing is greater than the non-Newtonian. A heterogeneity placed in the non-Newtonian convection forms horizontal structures, which may persist for at least 1 Ga on the upper-mantle scale. In addition, the non-Newtonian medium reveals a lesser amount of stretching of the lines than the Newtonian material. The rate of the Newtonian stretching fits well with an exponential dependence with time, while the non-Newtonian rheology shows the stretching rate close to a power-law dependence with time. In the Newtonian medium the heterogeneity is reorganized into two unstable vertical columns, while the non-Newtonian mixing favors horizontal structures. In the latter case, these structures are sufficiently stable in both the temporal and spatial planes to explain the mantle geochemical and geophysical heterogeneities. Due to the non-linear character of power-law rheology, the non-Newtonian medium offers a “natural” scale-dependent resistance to deformation, which prevents efficient mixing at the intermediate length scales.  相似文献   

Doubled CO₂ impact on subarctic marine carbon cycle: a case study at Ocean Station P     

K. Higuchi  Y. -H. Chan  C. W. Yuen  C. S. Wong 《Marine Chemistry》2000,72(2-4)

Along with meteorological observations, complementary and systematic oceanographic observations of various physical, biological and chemical parameters have been made at Ocean Station P (OSP) (50°N, 145°W) since the early 1950s. These decadal time scale data have contributed to a better understanding of the physical, biological and chemical processes in the surface layer of the northeastern subarctic region of the Pacific Ocean. These data have demonstrated the importance of the North Pacific in the global carbon cycle and, in particular, the role of biological/chemical processes in the net exchange of CO₂ across the air–sea interface. Although we do not fully comprehend how climatic variations influence marine communities or marine biogeochemistry, previous studies have provided some basic understanding of the mechanisms controlling the seasonal and inter-annual variations of biological and chemical parameters (such as phytoplankton, bacteria, nitrate/ammonium concentration) at OSP, and how they affect the carbon cycling in the subarctic North Pacific. In this study, we investigate how these mechanisms might alter the seasonal variations of these parameters at OSP under a 2XCO₂ condition. We examine these influences using a new biological model calibrated by the climatological data from OSP. For the 2XCO₂ simulation, the biological model is driven off line (i.e., no feedback to the ocean/atmospheric model components) by the climatology plus 2XCO₂−1XCO₂ outputs from a global surface ocean model and the Canadian GCM. Under the 2XCO₂ condition, the upper layer ocean shows an increase in the entrainment rate at the bottom of the mixed layer for OSP during the late autumn and winter seasons, resulting in an increase in the f-ratio. Although there is an overall increase in the primary production (PP) by 3–18%, a decrease in the biomass of small phytoplankton and microzooplankton (due to mesozooplankton grazing) lowers the concentration of dissolved organic matter (DOM) by 4–25%. The model also predicts a significant increase in the concentrations of nitrate and ammonium, and in bacterial production during July and August. Doubling of the atmospheric CO₂ from 330 to 660 ppm forces the marine pCO₂ to increase by about 63%, much of which is driven by an increased flux of CO₂ from the atmosphere to the oceans.  相似文献   

Secondary upwelling instabilities developed in high Rayleigh number convection: Possible applications to hot spots     

Marylee S. Murphy  Ludek Vecsey  Erik O. Sevre  David A. Yuen 《Visual Geosciences》2000,5(4):1-10

We have conducted numerical experiments for mantle convection in an axisymmetrical spherical-shell geometry from Rayleigh numbers ranging from three million to 10 billion for a purely basal heating configuration. We focus on the development of secondary instabilities developed from plumes and compare them with laboratory experiments by Skilbeck and Whitehead (1978) and Whitehead, (1982). For Rayleigh numbers between around thirty million to one billion, a string of these secondary instabilities can develop from a single plume. Analysis of the spectrum of wavelength associated with the fold instabilities shows that there is a window in the Rayleigh number between around ten million and one bilion where these secondary folding instabilities would develop. These results, when applied to the upper mantle, may explain the formation of hot-spots in a turbulently convecting upper-mantle with a Rayleigh number greater than ten million.  相似文献   

Evaluation of drainage tunnel effectiveness in landslide control     

Hong-yue Sun  Louis Ngai Yuen Wong  Yue-quan Shang  Yong-jiang Shen  Qing Lü 《Landslides》2010,7(4):445-454

Infiltration of rainfall into hillslopes is often an important factor in triggering landslides. Using underground water drainage works together with anti-slide piles has been an effective method of landslide control, yet their effectiveness is inadequately discussed in the literature. This paper studies the influence of rainfall on the change in the underground water level beneath a slope by real-time and synchronic monitoring of the rainfall, the underground water level in the boreholes, and the flow rate of the underground drainage tunnel. The effectiveness of the underground drainage tunnel in preventing the rise of the underground water level of the slope is discussed. The researchers also study the deformation behavior of the anti-slide piles by monitoring the lateral displacement of the piles and analyzing the thrust that the anti-slide piles bear by numerical inversion techniques. The results indicate that there is an apparent relationship between the lag in the rising of the underground water level caused by a rainfall and that caused by the immediately previous rainfall. When there is a rainfall accumulation before the occurrence of a heavy rain, this particular heavy rainfall will cause a rapid rise of the underground water level beneath the slope. The monitoring data analysis shows that the flow rate of the underground drainage tunnel increases first, and then the underground water level of the slope rises after a rainfall. In other words, the flow rate of the underground drainage tunnel increases at a rate faster than that of the rise of the underground water level. Hence, the underground drainage tunnel can effectively lower the rise of the underground water level induced by a rainfall. Besides, based on the monitoring data of the lateral displacement of the anti-slide piles and subsequent analysis, the working state of the anti-slide piles is justified. It thus indirectly validates the benefits of using underground drainage tunnel in landslide control.  相似文献   

气候变化及人类活动对中国北方岩溶泉的影响——以山西柳林泉为例   总被引：5，自引：0，他引：5  

郝永红  王玮  王国卿  杜欣  朱宇恩  王学萌 《地质学报》2009,83(1)

中国是岩溶最发育的国家之一,全球岩溶面积的1/4分布在中国.由于岩溶含水层对环境变化非常敏感,岩溶泉已经成为人们研究气候变化与人类活动对环境影响的重要信息载体.本文以中国北方具有代表性的柳林泉为研究对象,经过分析认为1957～1973年泉水流量基本上处于自然状态,因此,我们利用1973年前的泉水流量,建立了气候变化条件下泉水流量的灰色系统模型,将该模型外推,获得了1974～2005年气候变化条件下的泉水流量,与同期实测流量相比较,得到了人类活动对泉水流量衰减的贡献.结果表明,1974～2005年,气候变化对泉水流量衰减的贡献仅为人类活动对泉水流量衰减贡献量的8.1%～8.6%,人类活动对泉水流量的衰减起着主要作用.在人类活动对泉水流量的影响中,地下水开采量仅占到其中的20%～35%;其他因素包括水库的修建、跨区域地下水袭夺、矿坑排水、泉域内森林植被的破坏等等,他们对泉水流量衰减的贡献占到65%～80%.因此,传统的单纯以地下水开采量作为人类活动对泉水的影响是不合理的.  相似文献