分数阶傅里叶变换联合支持向量机的建筑物变形预测

提出一种分数阶傅里叶变换(fractional Fourier transformation, FrFT)与支持向量机(support vector machine, SVM)相结合的建筑物变形组合预测模型。首先利用FrFT对变形时间序列进行多尺度分析,将复杂时间序列分解为一系列结构较为简单的子序列;然后利用SVM对每个子序列分别建立预测模型,通过将各个子序列的预测结果进行综合叠加,得到最终预测结果;同时考虑到SVM模型参数选择的难题,提出一种改进果蝇优化算法(improved fruit fly optimization algorithm, IFOA)对其进行全局寻优,提升预测性能。以西南地区某混凝土坝变形实测数据为例开展验证实验,结果表明,本文组合预测模型能够充分挖掘数据中隐含的趋势性和规律性信息,获得较高的预测精度。     

New Late Jurassic palaeomagnetic data from the northern Sichuan basin: implications for the deformation of the Yangtze craton

Upper Jurassic red sandstones and red siltstones were collected from 67 layers at 12 localities in the Penglaizhen formation. This formation is in the north of Bazhong county (31.8°N, 106.7°E) in the Sichuan basin, which is located in the northern part of the Yangtze craton. Thermal demagnetization isolated a high-temperature magnetic component with a maximum unblocking temperature of about 690 °C from 45 layers. The primary nature of the magnetization acquisition is ascertained through the presence of magnetostratigraphic sequences with normal and reversed polarities, as well as positive fold and reversal tests at the 95 per cent confidence level. The tilt-corrected mean direction of 36 layers is D = 20.0°, I = 28.8° with α ₉₅ = 5.8°. A Late Jurassic palaeomagentic pole at 64.7°N, 236.0°E with A ₉₅ = 7.0° is calculated from the palaeomagnetic directions of 11 localities. This pole position agrees with the two other Late Jurassic poles from the northern part of the Yangtze craton. A characteristic Late Jurassic pole is calculated from the three poles (68.6°N, 236.0°E with A ₉₅ = 8.0°) for the northern part of the Yangtze craton. This pole position is significantly different from that for the southern part of the Yangtze craton. This suggests that the southern part of the Yangtze craton was subjected to southward extrusion by 1700 ± 1000  km with respect to the northern part. Intracraton deformation occurred within the Yangtze craton.     

Surface vertical displacements, potential perturbations andgravity changes of a viscoelastic earth model induced by internal point dislocations

Using the viscoelastic correspondence principle, we utilize the surface coseismic spheroidal deformation fields (i.e. vertical displacements, potential perturbations and gravity changes) of SNREI earth models caused by four typical types of point dislocation, derived by Sun & Okubo (1993 ), to deduce the fundamental formulas for spheroidal fields relevant to viscoelastic earth models. In computations, we employ a strike-slip dislocation on a vertical plane buried at the bottom of the lithosphere to estimate the maximal viscous relaxation responses to this kind of source that possibly exist on the surface of the earth. We take the seismic moment as 10²²  N  m, which is characteristic of an average large earthquake. The numerical results demonstrate that, if we take the viscosity as 10¹⁹  Pa  s in the asthenosphere, and 10²¹  Pa  s in the other mantle layers, the rates of surface vertical displacements and gravity changes within about 2.5° for the 10 postseismic years are respectively 1.5–8.1  cm  yr⁻¹ and 4.0–14.9  μgal  yr⁻¹ : the viscous relaxation for this mantle viscosity profile proceeds much faster than for a constant mantle viscosity of 10²¹  Pa  s.     

扬子地台西北缘前陆逆冲带及煤田构造特征

扬子地台西北缘前陆逆冲带(即龙门山逆冲带)的形成和演化控制着扬子地台内部及其西北缘煤炭资源的聚积和赋存。它可分为根带、中带、锋带三部分。根带无煤聚积,工业煤炭资源赋存在中带,锋带的煤系埋藏过深。前陆逆冲带内的煤田构造变形是适应前陆逆冲挤压应力作用的结果,以发育有冲断叠瓦扇、双冲构造、平行褶皱、斜歪褶皱、飞来峰、逆冲岩席、断夹块等构造样式为特征。前陆逆冲带的形成是特提斯构造域长期演化、沿三条缝合带发生三次碰撞的结果。      

晋冀蒙地区的垂直形变特征

基于1998、2006和2013年3期水准复测资料,平差计算得到1998~2006年和2006~2013年的垂直形变速率及其垂直形变速率梯度。根据计算结果研究晋冀蒙地区的地壳垂直形变运动趋势以及主要断裂带的活动性,分析区域垂直形变速率和垂直形变速率梯度的演变。结果揭示出吕梁山地块后一时段上升速率增加、太行山地块由前一时段上升变为后一时段下降、盆地地带变化复杂的垂直形变态势。     

岩石变形图像分析的计算机统计方法初探

本文利用岩石变形形成的显微构造现象(如压力影、亚颗粒、位错、动态重结晶颗粒等),通过图象分析计算机数理统计方法,来推测地质体变形特征、变形环境、应力状态等。      

核电厂取水明渠泥沙回淤分析

核电厂需用大量冷却水,用水量为工业用水的第一位。明渠取水是核电厂常用的取水方式之一。本文针对电厂取水明渠及口门外水流特点,分析计算了取水明渠内各部位及口门外过渡段的泥沙回淤率,并提出减少明渠泥沙回淤量的措施。     

被动陆缘盆地陆隆斜坡对盐构造形成的影响 ——来自物理模拟实验的启示

被动陆缘盆地盐构造形成的影响因素及时空演化分析受到了国内外学者的高度重视.丰富的油气资源促进了被动陆缘盆地地震资料品质的不断提升,高精度地震数据的解译结果表明,被动陆缘盆地盐层下的地形往往具有大型的起伏特征,而前人在基底构造形态对盐构造形成影响方面的研究并未取得共识,仍需要深入研究和探讨.为此,本文基于前人的研究认识,...     

人工观测与自动观测地面最低温度的差异分析

分析在地面温度下降到零度以下时,自动站的地面最低温度与人工站的地面最低温度差异明显增大的原因,为两者资料能正确应用提供依据。