高层高强钢组合偏心支撑框架抗震性能简化分析          下载免费PDF全文

洪敏  秦瑞  王凤  高永国  高中南  李少华 《地震工程学报》2020,42(2):332-336

高强钢组合偏心支撑钢框架是一种新型的抗震结构体系,为分析其抗震性能,利用ABAQUS有限元软件建立了简化分析模型。在验证该简化模型合理有效的基础上,建立了某十层算例的整体模型,施加竖向荷载的同时施加水平倒三角形循环荷载作用,进而分析了该算例的滞回性能。研究表明:本文提出的简化分析模型不仅可以较准确的模拟该结构体系的延性和抗侧刚度,还可以有效预测结构的变形分布和非线性性能。  相似文献   

基于TerrSolid对机载雷达DEM重提取方法研究     

王瑚  周光耀  周海龙 《测绘与空间地理信息》2020,(3):127-130

DEM的提取是激光雷达数据采集的重要用途之一,但由于目前算法的局限性,无法高精度地自动分类,如何在算法分类的基础上重新进行人工分类,以一定的原则和标准进行重提取从而得到更高精度的DEM,仍然是专业领域的一大难题。本文对某.LAS数据重提取,极大提高了其DEM的精度,为今后相关单位和个人使用TerrSolid软件对机载雷达DEM重提取提供一些经验。  相似文献   

广西土壤有机质空间变异特征及其影响因素研究   总被引：2，自引：0，他引：2  

钟聪  李小洁  何园燕  邱微文  李杰  张新英  胡宝清 《地理科学》2020,40(3):478-485

基于广西第二次土壤普查的270个土壤剖面资料,结合1∶50万数字化土壤类型图、土地利用类型图和气象监测数据等资料,利用地统计学和逐步回归分析等方法对广西表层土壤有机质空间变异特征及其影响因素进行了探究。结果表明：广西表层土壤有机质平均含量为3.11±2.19%,变异系数为70.72%,空间分布呈北高南低的趋势。广西表层土壤有机质空间分布受到自然和人为因素的共同影响,土壤类型、成土母质、海拔、土地利用、气候和坡度6个环境因子对全区土壤有机质含量变异的综合解释能力为47.9%。其中,土壤类型是最重要的影响因素,能独立解释其变异的36.0%,海拔和成土母质分别能独立解释28.5%和15.8%。气温对广西土壤有机质空间分布的影响比降水量更加显著,从而造成了广西土壤有机质整体呈南低北高的趋势。同时,土壤有机质对气温的敏感性在一定程度上受到降雨量的制约。此外,研究区农业耕作管理等因素对土壤有机质的影响也不容忽视。  相似文献   

1966—2018年河西走廊春季寒潮频次及影响因子分析          下载免费PDF全文

吕青松  辛存林  王瑞  张勃  张华 《干旱区地理》2020,43(4):946-954

基于甘肃河西走廊15个国家基准基本站点提供的1966年1月1日~2018年12月31日春季（3~5月）逐日最低气温值数据,利用线性回归分析方法、Spline空间插值法和Mann-Kendall趋势和突变检验法,探讨了河西走廊地区1966—2018年春季（3~5月）寒潮频次变化及其影响因子。研究表明：（1） 1966—2018年河西走廊地区春季（3~5月）单站寒潮频次总体呈现下降趋势〔–0.098次·（10 a）^–1〕,其中1980—2010年寒潮频次呈显著下降趋势,2010年之后下降趋势变缓,未通过显著性检验;区域寒潮53 a来频次总体呈缓慢下降趋势〔–0.015次·（10 a）^–1〕。（2） 近53 a河西走廊地区春季三个月中,单站寒潮总量4月>3月>5月,其中4月、5月寒潮频次下降不明显,3月频次下降显著。（3） 空间上,大致以北大河和黑河干流为界,两河中间区域春季寒潮频次低,而北大河以北和黑河干流以东区域则是寒潮高值区,走廊外围地区寒潮频次较高,且大多呈显著下降趋势,寒潮频次与气温距平存在明显负相关关系,内部地区变化趋势不明显。（4） 河西地区春季寒潮频次受气候变暖、地形和大气环流的影响,寒潮频次变化趋势存在地区差异。研究可提高对甘肃河西走廊寒潮演化过程的认知,为河西走廊气候变化的进一步研究奠定基础。  相似文献   

基于住房需求意愿的广州市中产阶层住房区位选择     

边艳  周春山  胡锦灿 《热带地理》2020,40(5):832-842

以2014年广州市中产阶层聚居区24个街道、50个社区进行的问卷调查和深度访谈资料为数据源，从住房需求意愿与区位选择方面分析了广州中产阶层住房选择，并运用多元Logistic回归分析法对其影响因素进行研究。研究发现：1）广州市中产阶层住房区位选择表现出明显的“向中心城区”性；2）现居住现状（人均住房面积、现小区区位、现小区建成年代、现居住时间）、家庭生命周期（年龄、家庭规模、子女数量）和经济水平（家庭年总收入、个人年总收入、私家车拥有量）等因素对中产阶层住房需求意愿具有显著影响；3）家庭生命周期（年龄、家庭规模）、个体因素（教育程度、户籍地）等要素对中产阶层住房区位选择具有显著影响。4）制度因素、区位因素和个体因素共同影响着广州市中产阶层住房区位选择。  相似文献   

Influence of Stress on Void Ratios of Compacted Crushed Rock Masses in Coal Mine Gobs     

Hu  Shengyong  Han  Dandan  Feng  Guorui  Zhang  Ao  Hao  Guocai  Hu  Lanqing  Zhu  Liping  Li  Bo 《Natural Resources Research》2020,29(2):1361-1373

The transfer and evolution of stress among rock blocks directly change the void ratios of crushed rock masses and affect the flow of methane in coal mine gobs. In this study, a Lagrange framework and a discrete element method, along with the soft-sphere model and EDEM numerical software, were used. The compaction processes of rock blocks with diameters of 0.6, 0.8, and 1.0 m were simulated with the degrees of compression set at 0%, 5%, 10%, 15%, 20%, and 25%. This study examines the influence of stress on void ratios of compacted crushed rock masses in coal mine gobs. The results showed that stress was mainly transmitted downward through strong force chains. As the degree of compression increased, the strong force chains extended downward, which resulted in the stress at the upper rock mass to become significantly higher than that at the lower rock mass. It was determined that under different degrees of compression, the rock mass of coal mine gobs could be divided, from the bottom to the top, into a lower insufficient compression zone (ICZ) and an upper sufficient compression zone (SCZ). From bottom to top, the void ratios in the ICZ sharply decreased and those in the SCZ slowly decreased. Void ratios in the ICZ were 1.2–1.7 times higher than those in the SCZ.

  相似文献   

Modeling studies of tidal dynamics and the associated responses to coastline changes in the Bohai Sea,China     

Longhai Zhu  Rijun Hu  Haijun Zhu  Shenghui Jiang  Yongchen Xu  Nan Wang 《Ocean Dynamics》2018,68(12):1625-1648

Over the past 30 years, reclamation projects and related changes have impacted the hydrodynamics and sediment transport in the Bohai Sea. Three-dimensional tidal current models of the Bohai Sea and the Yellow Sea were constructed using the MIKE 3 model. We used a refined grid to simulate and analyze the effects of changes in coastline, depth, topography, reclamation, the Yellow River estuary, and coastal erosion on tidal systems, tide levels, tidal currents, residual currents, and tidal fluxes. The simulation results show that the relative change in the amplitude of the half-day tide is greater than that of the full-day tide. The changes in the tidal amplitudes of M₂, S₂, K₁, and O₁ caused by coastline changes accounted for 27.76–99.07% of the overall change in amplitude from 1987 to 2016, and water depth changes accounted for 0.93–72.24% of the overall change. The dominant factor driving coastline changes is reclamation, accounting for 99.55–99.91% of the amplitude changes in tidal waves, followed by coastal erosion, accounting for 0.05–0.40% of the tidal wave amplitude changes. The contribution of changes in the Yellow River estuary to tidal wave amplitude changes is small, accounting for 0.01–0.12% of the amplitude change factor. The change in the highest tide level (HTL) is mainly related to the amplitude change, and the correlation with the phase change is small. The dominant factor responsible for the change in the HTL is the tide amplitude change in M2, followed by S2, whereas the influence of the K1 and O1 tides on the change in the HTL is small. Reclamation resulted in a decrease in the vertical average maximum flow velocity (V_VAM) in the Bohai Sea. Shallower water depths have led to an increase in the V_VAM; deeper water depths have led to a decrease in the maximum flow velocity. The absolute value of the maximum flow velocity gradually decreases from the surface to the bottom, but the relative change value is basically constant. The changes in the tidal dynamics of the Bohai Sea are proportional to the degree of change in the coastline. The maximum and minimum changes in the tidal flux appear in Laizhou Bay (P-LZB) and Liaodong Bay (P-LDB), respectively. The changes in the tidal flux are related to the change in the area of the bay. Due to the reduced tidal flux, the water exchange capacity of the Bohai Sea has decreased, impacting the ecological environment of the Bohai Sea. Strictly controlling the scale of reclamation are important measures for reducing the decline in the water exchange capacity of the Bohai Sea and the deterioration of its ecological environment.  相似文献   

A simplified method for analyzing the fundamental frequency of monopile supported offshore wind turbine system design     

Chunbao Yang  Rui Wang  Jianmin Zhang 《地震工程与工程振动(英文版)》2018,17(4):893-901

Preliminary design of offshore wind turbines requires high precision simplified methods for the analysis of the system fundamental frequency. Based on the Rayleigh method and Lagrange's Equation, this study establishes a simple formula for the analysis of system fundamental frequency in the preliminary design of an offshore wind turbine with a monopile foundation. This method takes into consideration the variation of cross-section geometry of the wind turbine tower along its length, with the inertia moment and distributed mass both changing with diameter. Also the rotational flexibility of the monopile foundation is mainly considered. The rigid pile and elastic middle long pile are calculated separately. The method is validated against both FEM analysis cases and field measurements, showing good agreement. The method is then used in a parametric study, showing that the tower length Lt, tower base diameter d0, tower wall thickness δt, pile diameter db and pile length Lb are the major factors influencing the fundamental frequency of the offshore wind turbine system. In the design of offshore wind turbine systems, these five parameters should be adjusted comprehensively. The seabed soil condition also needs to be carefully considered for soft clay and loose sand.  相似文献   

Ground roll attenuation based on an empirical curvelet transform     

Huan Yuan  Zi-Duo Hu  Zhao Liu  Jian-Wei Ma 《应用地球物理》2018,15(1):111-117

In the field of seismic exploration, ground roll seriously affects the deep effective reflections from subsurface deep structures. Traditional curvelet transform cannot provide an adaptive basis function to achieve a suboptimal denoised result. In this paper, we propose a method based on empirical curvelet transform (ECT) for ground roll attenuation. Unlike the traditional curvelet transform, this method not only decomposes seismic data into multiscale and multi-directional components, but also provides an adaptive filter bank according to frequency content of seismic data itself. So, ground roll can be separated by using this method. However, as the frequency of reflection and ground roll components are close, we apply singular value decomposition (SVD) in the curvelet domain to differentiate the ground roll and reflection better. Examples of synthetic and field seismic data reveal that the proposed method based ECT performs better than the traditional curvelet method in terms of the suppression of ground roll.  相似文献   

多点液压式波浪能海水淡化系统建模与仿真   总被引：1，自引：1，他引：0  

胡缘  杨绍辉  何宏舟  陈沪  郑松根  张迪 《海洋工程》2019,37(1):134-141

为缓解淡水资源短缺及化石能源过度使用问题,提出多点液压式波浪能海水淡化系统,该系统主要由采能装置、液压传递系统与反渗透膜海水淡化设备组成。系统的采能装置采用振荡浮子式,可将波浪能转换为浮子振荡从而被液压系统吸收达到采集波浪能的目的。为了提高液压式波浪能海水淡化系统的采能效率及淡水率,利用AMEsim软件对液压传递系统进行建模与仿真,分析了蓄能器、浮子个数及波高对液压传递系统输出响应的影响。结果表明:蓄能器能够使液压马达的输出响应更加稳定;当浮子的数量增加时,液压系统达到稳定的运行状态所需的时间更短,从而有利于提高系统的效率;波高在2 m左右时,本系统的产水量达到最大。  相似文献