A time‐domain seismic SSI analysis method for inelastic bridge structures through the use of a frequency‐dependent lumped parameter model

It is highlighted in the past that the soil–structure interaction phenomenon can produce a significant alteration on the response of a bridge structure. A variety of approaches has been developed in the past, which is capable of tackling the soil–structure interaction problem from different perspectives. The popular approach of a discretized truncated finite element model of the soil domain is not always a numerically viable solution, especially for computationally demanding simulations such as the probabilistic fragility analysis of a bridge structure or the real time hybrid simulation. This paper aims to develop a complete modeling procedure that is capable of coping with the soil–structure interaction problem of inelastic bridge structures through the use of a frequency dependent lumped parameter assembly. The proposed procedure encounters accuracy and global stability issues observed on past methods while maintaining the broad applicability of the method by any commercial FEM software. A case study of an overpass bridge structure under earthquake excitations is illustrated in order to verify the proposed method. Copyright © 2015 John Wiley & Sons, Ltd.     

Storm surge prediction using an artificial neural network model and cluster analysis

In this study, an artificial neural network model was developed to predict storm surges in all Korean coastal regions, with a particular focus on regional extension. The cluster neural network model (CL-NN) assessed each cluster using a cluster analysis methodology. Agglomerative clustering was used to determine the optimal clustering of 21 stations, based on a centroid-linkage method of hierarchical clustering. Finally, CL-NN was used to predict storm surges in cluster regions. In order to validate model results, sea levels predicted by the CL-NN model were compared with results using conventional harmonic analysis and the artificial neural network model in each region (NN). The values predicted by the NN and CL-NN models were closer to observed data than values predicted using harmonic analysis. Data such as root mean square error and correlation coefficient varied only slightly between CL-NN and NN model results. These findings demonstrate that cluster analysis and the CL-NN model can be used to predict regional storm surges and may be used to develop a forecast system.     

Occurrence of gorgosterol in diatoms of the genus Delphineis

The presence of the C₃₀ sterol gorgosterol (22,23-methylene-23,24-dimethylcholest-5-en-3ß-ol) and its analogues in some marine and freshwater environments is generally associated with invertebrate animals or dinoflagellates since there have been no reports of them in other microalgal classes. Here we show that two unialgal cultures of different species of the marine diatom Delphineis contain gorgosterol in addition to sterols more commonly found in diatoms. Our findings suggest that some reports of gorgosterol in seawater and marine sediments may well have an origin, at least in part, from diatoms.     

地壳岩石的失水熔融实验

以岩石粉末试样的熔融实验为基础的 Ｑ Ａｂ Ｏｒ Ａｎ Ｈ２ Ｏ 体系的相关系表明,地壳岩石的熔融作用遵循矿物相消失所制约的固 液相平衡规律。然而,地壳岩石块状样品开放体系的熔融作用,其熔融机制、矿物相转变、初熔液相成分、残余固相等方面,均与地壳岩石封闭体系的熔融作用有很大差别。石英闪长岩开放体系的熔融实验表明,岩石的熔融首先从含水矿物的脱水熔融开始,从而熔体成分由基性逐渐转变为中酸性,残余固相趋于超酸性。这一实验结果对大陆地区岩浆起源和深部地壳物质组成的研究可能有新的启示。     

Role of tropical atlantic SST variability as a modulator of El Niño teleconnections

The present study suggests that the off-equatorial North Atlantic (NATL) SST warming plays a significant role in modulating El Niño teleconnection and its impact on the North Atlantic and European regions. The El Niño events accompanied by NATL SST warming exhibit south-north dipole pattern over the Western Europe to Atlantic, while the ENSO teleconnection pattern without NATL warming exhibits a Rossby wave-like pattern confined over the North Pacific and western Atlantic. Especially, the El Niño events with NATL warming show positive (negative) geopotential-height anomalies over the North Atlantic (Western Europe) which resemble the negative phase of the NAO. Consistently, it is shown using a simple statistical model that NATL SSTA in addition to the tropical Pacific SSTA leads to better prediction on regional climate variation over the North Atlantic and European regions. This role of NATL SST on ENSO teleconnection is also validated and discussed in a long term simulation of coupled global circulation model (CGCM).     

Probabilistic stability analyses of slopes using the ANN-based response surface

Slope stability analysis is a geotechnical engineering problem characterized by many sources of uncertainty. Some of these sources are connected to the uncertainties of soil properties involved in the analysis. In this paper, a numerical procedure for integrating a commercial finite difference method into a probabilistic analysis of slope stability is presented. Given that the limit state function cannot be expressed in an explicit form, an artificial neural network (ANN)-based response surface is adopted to approximate the limit state function, thereby reducing the number of stability analysis calculations. A trained ANN model is used to calculate the probability of failure through the first- and second-order reliability methods and a Monte Carlo simulation technique. Probabilistic stability assessments for a hypothetical two-layer slope as well as for the Cannon Dam in Missouri, USA are performed to verify the application potential of the proposed method.     

Genetic Implications of Two Different Ultramafic Rocks from Hongseong Area in the Southwestern Gyeonggi Massif, South Korea

Two distinct ultramafic bodies occur in Baekdong and Bibong in the Hongseong area within Gyeonggi massif of South Korea. The Hongseong area is now extensively documented as an extension of the Dabie-Sulu collision belt in China. The Baekdong ultramafic body has a NWW elongation direction. This elongation trend is similar to the general trend of the Dabie-Sulu collision belt. The Bibong ultramafic body is elongated in a NNE direction and runs parallel to the direction of the main fault in the study area. The Baekdong ultramafic bodies show porphyroclastic and mylonitic textures while those at Bibong exhibit a mosaic texture. Both were grouped into peridotite and serpentinite based on their modal abundance of serpentine. In the olivine (Fo) vs. spinel [Cr# = Cr/ (Cr+Al)] diagram, both ultramafic rocks fall with in olivine spinel mantle array. The compositions of olivine, orthopyroxene and spinel indicate that the Baekdong ultramafic rock formed in deeper parts of the upper-mantle under passive margin tectonic setting. The SREE content of Baekdong ultramafic rock vary from 0.19 to 5.7, exhibits a flat REE pattern in the chondrite-normalized diagram, and underwent 5% partial melting. Conversely, large variation in SREE (0.5 21.53) was observed for Bibong ultramafic rocks with an enrichment of LREE with a negative slope and underwent 17 24% partial melting. The Baekdong ultramafic rocks experienced three stages of metamorphism after a high pressure residual mantle stage. The first stage of metamorphism occurred under the eclogite-granulite transitional facies (1123 911°C, >16.3 kb) the second under the granulite facies (825 740°C, 16.3 11.8 kb) and the third is the retrogressive metamorphism under amphibolite facies (782 718°C, 8.2 8.7 kb) metamorphism. The Baekdong ultramafic rocks had undergone high-P/T metamorphism during subduction of the South China Block, and experienced a fast isothermal uplift, and finally cooled down isobarically. Evidences for metamorphism were not identified in Bibong ultramafic rocks. Hence, the Baekdong ultramafic rocks with in the Hongseong area may indicate a link on the Korean counterpart of Dabie-Sulu collision belt between North and South China Blocks.