Determination of silica sand stiffness

Site investigation and evaluation of properties of soil or rock are important aspects of geotechnical design. Determination of the ground stiffness is one of the important parameters in geotechnical engineering. Since the measurement of shear modulus is very sensitive to soil disturbance, especially for sand, determination of the stiffness of soil in the field is more reliable than in laboratory tests on sampled specimens. Measurement of shear modulus is one of the most common applications of self-boring pressuremeter testing. As an in situ device, the pressuremeter provides a unique method for assessing directly the in situ shear modulus of a soil. This paper describes a laboratory study of silica sand stiffness, which varies with stress level and strain amplitude. The results show that the elastic shear modulus value is mainly dependent on the value of the mean effective stress and relative density.     

Early Ordovician Sea Level Changes in South China and Their Worldwide Correlation

INTRODUCTIONTheoaf~ansed~arewidelydistributedinSouthetna,fromtheYanalCratondPborminnorthtocontinentalmarginofsoutheastern~insouth.ThePreSentpaperdiscussesmainlytheEarlyOrdovidan(thehoeofHirmtodontussimplex~tothebaseofNemopagngraciliszone,Wangatal.,1992)sealeVelchangeSandtheirworldwidecorrelationbasedonasyntheticalstudyofseqUenCe,bioshatiglaphyandaretratigl'aphy.Thisapproachwillfillinthe~instudyoftheOrdovidanofChina,andimprovethesu~ionandCO~ionofbio--,litho--andcbronostheigraphy.Mea…     

Modelling transverse dunes

Transverse dunes appear in regions of mainly unidirectional wind and high sand availability. A dune model is extended to two‐dimensional calculation of the shear stress. It is applied to simulate dynamics and morphology of three‐dimensional transverse dunes. In the simulations they seem to reach translational invariance and do not stop growing. Hence, simulations of two‐dimensional dune ?elds have been performed. Characteristic laws were found for the time evolution of transverse dunes. Bagnold's law of the dune velocity is modi?ed and reproduced. The interaction between transverse dunes led to the interesting conclusion that small dunes can travel over bigger ones. Copyright © 2004 John Wiley & Sons, Ltd.     

沈阳地区沙尘天气分析

本文总结了沈阳地区沙尘天气的时空分布特点，从天气条件、地表自然条件(沙源)两方面分析了沈阳地区沙尘天气的成因，总结了沈阳地区预报沙尘天气时应参考的5个因素。     

Effect of shipping activity on warming trends in the Canadian Arctic

This paper presents a detailed account of the effect of shipping activity on the increasing trends of air temperatures in the Canadian Arctic region for the period of 1980–2018. Increasing trend of temperature has gained significant attention with respect to shipping activities and sea ice area in the Canadian Arctic. Temperature, sea ice area and shipping traffic datasets were investigated, and simple linear regression analyses were conducted to predict the rate of change(per decade) of the average temperature, considering winter(January) and summer(July) seasons. The results indicate that temperature generally increased over the studied region. Significant warming trend was observed during July, with an increase of up to 1℃, for the Canadian Arctic region. Such increasing trend of temperature was observed during July from the lower to higher latitudes. The increase in temperature during July is speculated to increase the melting of ice. Results also show a decline in sea ice area has a significant positive effect on the shipping traffic, and the numbers of marine vessel continue to increase in the region. The increase in temperature causes the breaking of sea ice due to shipping activities over northern Arctic Canada.     

预测有效波高的深度学习模型研究

研究基于RNN、LSTM、GRU深度学习模型,针对NOAA浮标数据集中的44013、44014、44017浮标的数据,通过斯皮尔曼相关性分析提高模型预测效果。实验结果表明,在进行相关性分析后,S-RNN、S-LSTM、 S-GRU的预测效果均比原始RNN、LSTM、GRU模型预测效果好。此外,提出一种基于LSTM的LSTM-Attention 波高预测模型,并进行相关实验,量化LSTM-Attention模型的预测效果,实验结果表明LSTM-Attention模型有更好的预测效果。为评估模型的泛化能力,研究还提出了一种采用邻近浮标数据进行学习,预测浮标缺失数据的方 法。实验结果表明,该方法的预测精度可以达到97.93%。本研究为海浪预测提供了新的方法和思路,也为未来深 度学习模型在海浪预测中的应用提供了参考。