后张无粘结预应力混凝土简支板抗火分析

预应力混凝土板因具备自重轻、跨度大等特点,广泛应用于建筑结构和桥梁结构中。但是,当这种结构受到火灾荷载作用时,其承栽能力就会大幅下降。在高温下,混凝土和预应力筋的力学性能都会劣化,进而造成板的大挠度变形甚至破坏。本文对后张无粘结简支预应力板建立了数值分析模型,其中混凝土和预应力筋采用实体单元模拟,受力筋和分布钢筋采用桁架单元模拟。模型中材料的力学特性和热工特性参数取自文献[15]。采用文献中的试验结果验证了该数值模型的可靠性,并进一步研究了混凝土受热膨胀系数、板的不同区域受火和不同的火灾场景等因素对火灾荷载作用下后张无粘结预应力混凝土简支板的挠度以及预应力的影响,得出了初步结论。     

Field testing of the surface electromagnetic prospecting system

To test the performance of the Chinese whole-surface electromagnetic prospecting (SEP) system, system integrations, instrument performances, and large-scale production viabilities in Liaoning province and Inner Mongolia were measured via extensive field tests. Resultant electric fields, magnetic fields, apparent resistivities, impedance phases, and inversion profiles compared favorably with results of commercial equipment from other countries. The inversion results agreed well with the geologic information from boreholes. Field tests showed that the SEP system is stable, reliable, lightweight, and easy to operate, making it suitable and ready for real-field exploration.     

Wetlands of Northeast Asia and High Asia: an overview

This review reports background information on wetlands in the Northeast Asia and High Asia areas, including wetland coverage and type, significance for local populations, and threats to their vitality and protection, with particular focus on the relationship of how global change influenced wetlands. Natural wetlands in these areas have been greatly depleted and degraded, largely due to global climate change, drainage and conversion to agriculture and silviculture, hydrologic alterations, exotics invasions, and misguided management policies. Global warming has caused wetland and ice-sheet loss in High Asia and permafrost thawing in tundra wetlands in Northeast Asia, and hence induced enormous reductions in water-storage sources in High Asia and carbon loss in Northeast Asia. This, in the long term, will exacerbate chronic water shortage and positively feed back global warming. Recently, better understanding of the vital role of healthy wetland ecosystems to Asia’s sustainable economic development has led to major efforts in wetland conservation and restoration. Nonetheless, collaborative efforts to restore and protect the wetlands must involve not only the countries of Northeast and High Asia but also international agencies. Research has been productive but the results should be more effectively integrated with policy-making and wetland restoration practices under future climatic scenarios.     

大地震前体应变临震异常现象

本文对2011年1月至2014年4月间全球发生的80次MS≥7.0级地震前,二张营台和天堂河台Sacks体应变临震异常现象进行了研究,针对复杂震例提出了异常识别的前提条件。统计结果显示,体应变观测对震中距为8000km范围内的MS≥7.0级地震映震和前兆异常反映较好。同时,对异常现象进行了分类和描述,划分了三种异常类型：即固体潮畸变型、突变型和慢地震型,并对各种类型作了统计分析,进行了力学性质初步探讨。从研究结果来看,体应变异常信息对未来全球强震的发生具有一定的预示意义。     

The role of long‐term human impact on avulsion and fan development

This study aims to understand (mainly qualitatively) the long‐term role of human impact on avulsion processes and the development of fluvial (mega‐) fans in semi‐arid environments. In this paper we refer to human impact as the direct influences of actions on the river's hydraulics (i.e. flow regulation, flow diversion and channel engineering). In five case‐studies drawn from the Khuzestan plains in southwest Iran we have analysed the setup and triggering conditions of specific avulsions that occurred in the past (timescale of millennia) and identified the role of human interference in their causation. Our analysis is based on the integration of historical, archaeological, geomorphological and geological data. Through this study we demonstrate that avulsions in the Khuzestan plains are the result of long‐term and complex interplay between multiple human‐induced and natural causes. In similar ways human‐induced actions may play important roles during different phases of avulsion development. The ‘success‘ of an avulsion in the post‐triggering phase may be defined by human‐induced setup causes as well as morphodynamic processes. We suggest that present‐day flood events may be partly inherited from long‐term human alterations of the natural processes. These finding could have implications for any fluvial system (e.g. distributive fluvial systems, deltas) where avulsion plays a major role in their development and research tends to emphasize on natural mechanisms. Copyright © 2016 John Wiley & Sons, Ltd.     

基于改进的BP神经网络构建区域精密对流层延迟模型

利用神经网络算法挖掘海量数据的规律已成为科技发展的一种趋势,本文针对卫星信号的天顶对流层延迟进行建模.对流层延迟是影响卫星定位精度的重要因素之一,建立精密区域对流层模型对高精度定位有着重要的意义.对区域测站对流层延迟数据的分析,考虑到实时建模中传统BP（Back Propagation）神经网络计算量大,易出现"过拟合"现象、不稳定等因素,通过改进的BP神经网络建立了区域精密对流层模型.详细介绍了新模型的建立过程,并与常用的对流层区域实时模型进行了对比.还讨论了建模测站数目对预报精度的影响.相比现有的其他对流层延迟模型,基于改进的BP神经网络构建的区域精密对流层延迟模型无论在拟合和预报方面都有较好的精度,且随着测站数目的增加模型精度趋于平稳.改进的模型参数较少,可以进行实时的区域精密对流层延迟改正;需要播发的信息量小,适用于连续运行参考站系统（Continuously Operating Reference Stations,CORS）的应用.研究表明：改进的BP神经网络模型能够更好的充分利用大规模历史数据描述卫星信号对流层延迟的空间分布情况,适用于实时大区域精密对流层建模.基于日本地区2005年近1000多个测站的NCAR（National Center Atmospheric Research）对流层数据进行区域对流层延迟建模,结果表明改进的BP神经网络模型在拟合和预报精度上都有较大提升,RMSE（Root Mean Square Error）分别为：7.83 mm和8.52 mm,而四参数模型拟合、预报RMSE分别18.03 mm和16.60 mm.     

深吃水多立柱平台稳性与水动力分析

在深水平台的设计与分析中,调整某一结构参数提高某一性能的同时,常常受到其他功能或性能上的约束,因此引起了平台各项功能及性能之间的相互竞争。以一种创新的深吃水多立柱平台(Deep Draft Multi-Spar)为目标,探讨平台结构特征参数如立柱直径、立柱高度、立柱间距和压载舱位置与平台稳定性能、水动力及运动性能、结构要求和功能要求之间的关系。水动力分析和响应计算结果显示,随着DDMS平台吃水深度的降低,垂荡、纵摇和纵荡RAOs均逐渐增大,运动性能降低,并与典型的Spar和半潜平台的RAOs进行了比较。     

Experimental Study and Fatigue Analysis of Vortex-Induced Vibration of Umbilical Cable Considering Internal Friction

In order to investigate the effect of internal friction of umbilical cable on its vortex-induced vibration(VIV)responses, the experimental study on VIV of bond umbilical cable(BUC) and un-bond umbilical cable(UBUC) was carried out in an experimental tank. A current generator in the laboratory simulated the uniform current, and the current velocities were observed in real time by using a Doppler Velocimeter. In addition, different sizes of top tension were applied to the umbilical cable model. The VIV responses of the umbilical cable model were measured by using Fiber Bragg grating(FBG) strain sensors. The displacement responses of umbilical cable model were reconstructed based on the experimental strain data processed by modal superposition method. In this paper, the traveling wave characteristics, the spatial-temporal distribution characteristics of frequency and fatigue damage of the BUC and UBUC under VIV are studied. The experimental results show that there are obvious differences between BUC and UBUC in the response characteristics of VIV. The UBUC appears the traveling wave sooner than BUC, but its standing wave characteristics are more obvious than those of BUC at high velocities. Compared with BUC, the spatial-temporal distribution of UBUC frequencies appears wide-band distribution sooner, but has narrower bandwidth in the "lock-in" state. The level of fatigue damage of BUC was approximately the same as that of UBUC.     

南黄海盆地阜宁组烃源岩地层热压生烃特征

通过生烃模拟获取生烃动力学参数是近年来油气资源评价工作中极为重要的一个环节,利用地层热压生排烃模拟装置对南黄海盆地南二凹陷阜四段烃源岩进行了生烃模拟实验,并拟合了生烃动力学参数。实验及研究结果表明,阜四段烃源岩的生烃演化可分为3个阶段：第1阶段产烃量随温度上升快速增大,以产油为主;第2阶段产烃量随温度上升缓慢增加,为油、气同产;第3阶段产烃量随温度上升快速增大,主要是以生气为主。实验拟合出阜四段烃源岩的生油活化能为228 kJ/mol,生气活化能为280 kJ/mol。与常压—完全开放体系试验、金管-高压釜实验装置的实验结果对比,本次实验南黄海盆地阜四段烃源岩在地层热压条件下出现生油窗滞后现象,烃源岩样品在高成熟演化阶段依然具有较高的液态烃产率。阜四段生油活化能值较高,其内在原因是有机质受到烃源岩孔隙中高压水的“保护”作用以及受生烃空间的影响,延缓了烃源岩的热演化进程。综合前人实验结果分析,有限空间热压生烃模拟实验环境更接近于烃源岩在地层条件下的生烃条件,实验结果对南黄海盆地的油气资源潜力评价及油气勘探方向具有指导意义。     

铝土矿矿泥固化技术的试验研究

铝土矿选洗过程中排尾形成的高含水量矿泥,传统上采用建库堆存,泌干固结时间长,污染环境。试验研究结果表明,选用由72%水泥、20%石膏、5%石灰、3%硫酸钠组成的复合固化剂,或由72%石灰、20%石膏、5%粉煤灰、3%硫酸钠组成的复合固化剂,按固化剂与矿泥质量比1:10掺加,对矿泥进行固化处理,其固化体强度高、耐久性好,且成本低廉,具有广泛的工程应用价值。