基于贝叶斯优化机器学习超参数的滑坡易发性评价

利用机器学习模型进行滑坡易发性评价时,不同的超参数设置往往会导致评价结果的不同.采用贝叶斯算法对4种常见机器学习模型(逻辑回归LR、支持向量机SVM、人工神经网络ANN和随机森林RF)的超参数进行了优化,探索了该算法对滑坡易发性机器学习模型的优化效果.以湘中地区4县(安化县、新华县、桃江县和桃源县)滑坡易发性评价为例说...     

试论德宏宗教文化旅游开发

宗教文化既是人类文化的重要组成部分,又是旅游资源的重要组成部分,无论古今中外,人文旅游景观中的宗教文化内容都是游客为之注目的亮点。在新阶段,德宏州的旅游业要得到较大发展,就不能忽视宗教文化对旅游业的影响。在挖掘德宏州宗教文化旅游资源的基础上,初步探讨如何对德宏州宗教文化旅游资源进行开发利用的问题,对旅游业的发展具有重要的意义;而旅游业的发展,也有利于宗教文化的继承、传播、交流和研究,从而提出了建设德宏孔雀湖宗教园,将宗教文化打造为德宏旅游特有的一张名片。     

开封市不同功能区城市土壤有机碳含量与密度分析

研究开封城市土壤有机碳,发现不同功能区类型间及城区与郊区间的有机碳特性存在差异:土壤表层有机碳含量为工业区>休闲区>交通区>文教区>行政/居民区;表层有机碳密度为休闲区>工业区>交通区>文教>行政/居民区;土壤剖面有机碳密度为文教区>交通区>工业区>休闲区>行政/居民区.城市土壤表层有机碳密度和剖面有机碳密度均沿城郊剖面线呈下降式梯度变化,城区分别是郊区的2.53和1.56倍.城市土壤有机碳积累主要在地表之下0～30 cm范围内.     

辽宁数字化地震目录编辑

本文简述了基于MS Office套件的Excel和Word编制辽宁省地震目录编辑软件的过程,简介了辽宁省编辑地震目录软件的使用方法。该软件建立了通用的目录、报告数据库,定义出既完备又有利于检索和程序处理的库结构;编制了若干格式转换程序和自动入库程序。使多个来源于不同格式的数据,能自动合并到目录、报告数据库中;编制了基于通用目录、报告数据库的打印程序;编制了转换程序,在windows环境下实现上报国家地震局格式和适合辽宁地震预报使用需要的格式。     

岩溶地区不同利用方式土壤土力学特性垂直变化特征

以黔中岩溶地区不同利用方式的土壤为研究对象,采用野外调查和室内试验相结合的方法,研究了土壤黏聚力c、内摩擦角φ及紧实度随不同土壤利用方式、不同土层深度的变化特征。结果表明:土壤黏聚力c总体随土层深度不断增大,在0-35 cm内受不同土壤利用方式的影响比较明显;土壤内摩擦角φ在0-50 cm土层内,呈“S”形变化,受母质影响显著,三种不同土壤利用方式总体变化趋势基本一致;林地、灌草地、坡耕地土壤在垂直剖面上都存在着上松下紧的状况,在0-20 cm内,坡耕地土壤紧实度均小于林地和灌草地,20 cm以下坡耕地和灌草地土壤紧实度基本一致,但均大于林地,三者均保持着不断增大的趋势。研究表明:植被生长对于改善土壤力学性能具有一定的影响。因而通过加强植被保护与管理和调整坡耕地利用方式是改善土壤力学性能,防治土壤侵蚀和控制石漠化的主要手段。      

Assessment of the impact of anthropogenic activities on the groundwater hydrology and chemistry in Tarsus coastal plain (Mersin,SE Turkey) using fuzzy clustering,multivariate statistics and GIS techniques

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Highlights? Four distinct groundwater classes resulted from the fuzzy c-means clustering method. ? Both geogenic and anthropogenic processes affect the groundwater quality in the area. ? Salinization in the area is due to seawater intrusion and dissolution of evaporites. ? Near the coastal zone, the groundwater level is lowered 2–5 m below the sea level. ? Ancient subsurface hydrological features act as conduits for groundwater flow.     

山西地震带中小震精确位置及其显示的山西地震构造特征

利用山西1981-2001年模拟观测台网和2002-2008年间数字地震台网的震相数据,采用绝对定位方法和双差相对地震定位方法对山西及其周边地区中小地震进行了精确重新定位.结果表明: (1) 重新精确定位后,震中水平误差≤5 km的地震由原来65.8%提高到86.2%;7498次原始无震源深度的地震取得了深度结果.(2)精确定位后震中分布格局与原始结果相比变化不大,绝大多数地震集中在中部断陷盆地带内,两侧隆起区则相对较少,与山西地质构造的区域性和成带性相吻合;震源深度北浅南深,存在由北向南逐渐加深的特点. (3)重定位结果可以大致勾勒出各构造盆地发震层下界,较清晰地分辨出断陷盆地、盆间隆起的位置.(4)地震深度分布与盆山构造形态有较好的相关性.     

中低应变率下的岩石损伤本构模型研究

深部岩石的破碎与钻探中,岩石主要处在中低应变率的载荷作用下,而目前的研究还沿用中高应变率推导的动态损伤本构关系。从工程背景和试验角度分析了中低应变率下的岩石动力学特性,提出Maxwell体、Bingham体和损伤体的并联模型,借助拉普拉斯变换,引入基于岩石孔隙、裂隙劣化的损伤变量,导出了中低应变率下的岩石动态损伤本构模型。利用该模型对泥质砂岩和花岗岩在应变率为87 s-1、382 s-1、673 s-1时的应力-应变试验数据进行拟合,并将拟合结果与实测数值、原文献拟合曲线对比,结果表明该理论模型适用性较好。分析拟合参数可知,该动态损伤本构模型能够主动适应中低应变率两类情况,本构曲线和损伤变量的变化符合实际情况。     

Vehicle effects on seismic response of a simple‐span bridge during shake tests

Presence of vehicles on a bridge has been observed many times during past earthquakes. Although in practice, the engineers may or may not include the live load contribution to seismic weight in design, current bridge design codes do not specify a certain guideline. A very limited research has been conducted to address this issue from design point of view. The focus of this research is to experimentally assess the effect of a vehicle on the seismic response of a bridge through a large‐scale model. In this scope, a 12‐meter long bridge, having a one lane deck with concrete slab on steel girders, has been shaken under five different ground motions obtained from recent earthquakes that occurred in Turkey, in its transverse direction, both with and without a vehicle on top of the deck. The measured results have indicated that top slab transverse acceleration and bearing displacements can reduce up to 18.7% in presence of a vehicle during seismic tests, which is an indication of reduction in substructure forces. The main reason for the reduction in seismic response of the bridge in the presence of live load can be ascribed to the increase in damping of the system due to mass damper‐like action induced by the vehicle. This beneficial effect cannot be observed in vertical seismic response. Copyright © 2014 John Wiley & Sons, Ltd.     

Analysis of shear‐dominated RC columns using the nonlinear truss analogy

This paper uses nonlinear truss models for the analysis of shear‐dominated reinforced concrete (RC) columns subjected to cyclic loading. A previously established method, aimed to the analysis of RC walls, is enhanced to allow simulations of column members. The concrete constitutive equations are modified to account for the contribution of the aggregate interlock to the shear resistance. Additionally, an equation is proposed to determine the inclination angle of the diagonal members in the truss models. The modeling approach is validated using the results of quasi‐static and dynamic tests on shear‐dominated RC columns. The combination of predictive capabilities and conceptual simplicity establishes truss‐based models as an attractive approach for the systematic analysis of shear‐dominated RC frame construction. Copyright © 2014 John Wiley & Sons, Ltd.