G856磁力仪在地磁台站建设中的应用与实践方法

本文通过泉州地磁台重建工程中的工作实践,阐述了应用G856磁力仪在建筑材料磁性检测、施工过程中磁性跟踪监测的实践方法。     

台风路径数值预报模式的并行化及路径预报误差分析

国家气象中心台风路径数值预报模式经过串行优化及程序并行, 成功地实现了在国产超级计算机神威上的并行运算, 并可满足业务时效要求。基于并行程序及神威机计算平台的台风路径数值预报业务系统于2002年6月30日投入实时运行, 其初估场与侧边界条件从T106L19模式产品升级为T213L31模式产品 (称为基于T213台风预报系统, 原串行系统称为基于T106台风预报系统)。通过对2002年夏秋季台风路径的检验, 总体来看, 基于T213台风预报系统48 h内的平均路径预报误差小于基于T106台风预报系统的路径预报误差。对西行及西北行登陆的台风, 基于T106台风预报系统的48 h预报好于基于T213台风预报系统的预报。对于转向台风而言, 转向后的预报, 基于T213台风预报系统的预报要好于基于T106台风预报系统的预报, 有效地减小了基于T106台风预报系统对转向台风路径预报的系统性误差:即台风转向后预报路径较实况路径偏西。     

武汉市轨道交通二号线工程场地砂土液化分析

本文详细介绍了武汉市轨道交通二号线工程场地地震地质灾害评价中对饱和砂土液化的分析方法及评价结果。     

东海近海热带气旋及天气数值预报系统

以ＭＭ４模式为框架,研制并建立了东海近海热带气旋及天气数值预报系统,将对热带气旋的预报和一般天气的预报统一在一个模式中,并实现了业务自动化控制,自１９９４年台风季节起投入了业务试验和准业务的运行。结果表明：该系统对东海近海热带气旋路径、风场、降水及江淮梅雨降水具有较好的预报能力     

2004年台风“艾利”与“米雷”路径异常变化分析

2004年西北太平洋上生成的台风"艾利"和"米雷"开始都是向西北方向移动,当快要进入东海时两个台风的路径均发生变化,"艾利"转向西南方向,形成倒抛物线形的路径,而"米雷"突然向东北方向转折。通过对这两个台风的不同时间尺度环境场及其与台风相互作用的分析表明,对于西南转向的"艾利",副热带高压(副高)西伸明显,台风位于副高的南侧,天气尺度风场对副高低频分量的涡度平流,使得台风西北侧出现负涡度,同时由于罗斯贝波能量频散,台风东南侧出现负涡度,与负涡度相联系的天气尺度异常环流导致台风西北侧和东南侧的天气尺度引导气流的作用相互抵消,台风主要在低频环流引导下向西南方向移动;对于突然向东北转向的"米雷",副高位置偏东,转向时刻只有东南侧增强的天气尺度西南风,天气尺度引导气流导致台风向东北转折。     

A synergic algorithm for retrieval of aerosol optical depth over land

In this paper, a novel algorithm for aerosol optical depth(AOD) retrieval with a 1 km spatial resolution over land is presented using the Advanced Along Track Scanning Radiometer (AATSR) dual-view capability at 0.55, 0.66 and 0.87 μm, in combination with the Bi-directional Reflectance Distribution Function (BRDF) model, a product of the Moderate Resolution Imaging Spectroradiometer (MODIS). The BRDF characteristics of the land surface, i.e. prior input parameters for this algorithm, are computed by extracti...     

Simulated sensitivity of tropical cyclone track to the moisture in an idealized monsoon gyre

In this study, the sensitivity of tropical cyclone (TC) track to the moisture condition in a nearby monsoon gyre (MG) is investigated. Numerical simulations reveal that TC track is highly sensitive to the spatial distribution of relative humidity (RH). In an experiment conducted with higher (lower) RH in the eastern (western) semicircle of an MG, the TC experiences a sharp northward turning. In contrast, when the RH pattern is reversed, the simulated TC does not show a sharp northward turning. The RH distribution modulates the intensity and structure of both the TC and MG, so that when the TC is initially embedded in a moister environment, convection is enhanced in the outer core, which favors an expansion of the outer core size. A TC with a larger outer size has greater beta-effect propagation, favoring a faster westward translational speed. Meanwhile, higher RH enhances the vorticity gradient within the MG and promotes a quicker attraction between the TC and MG centers through vorticity segregation process. These cumulative effects cause the TC to collocate with the MG center. Once the coalescence process takes place, the energy dispersion associated with the TC and MG is enhanced, which rapidly strengthens southwesterly flows on the eastern flanks. The resulting steering flow leads the TC to take a sharp northward track.     

Full-scale model testing on a ballastless high-speed railway under simulated train moving loads

Model testing in laboratory, as an effective alternative to field measurement, provides valuable data to understand railway׳s dynamic behaviors under train moving loads. This paper presents comprehensive experimental results on track vibration and soil response of a ballastless high-speed railway from a full-scale model testing with simulated train moving loads at various speeds. A portion of a realistic ballastless railway comprising slab track, roadbed, subgrade, and subsoil was constructed in a larger steel box. A computer-controlled sequential loading system was developed to generate equivalent vertical loadings at the track structure for simulating the dynamic excitations due to train׳s movements. Comparisons with the field measurements show that the proposed model testing can accurately reproduce dynamic behaviors of the track structure and underlying soils under train moving loads. The attenuation characteristics of dynamic soil stresses in a ballastless slab track is found to have distinct differences from that in a ballasted track. The model testing results provide better understanding of the influence of dynamic soil–structure interaction and train speed on the response of track structure and soils.     

地铁控制基标归化改正原理及编程实现

介绍了控制基标在地铁建设中的作用和测设步骤,总结了铺轨基标归化改正计算的理论依据和基本计算方法,建立了数学模型。同时在VB6.0环境下编程,实现了归化改正点位的自动判定以及改正值的自动计算,介绍了编程原理,并提供了流程图及工程实例。     

Prediction of railway ground vibrations: Accuracy of a coupled lumped mass model for representing the track/soil interaction

Recent advances in railway-induced ground vibrations showed that the track/soil interaction plays an important role in the low frequency range. This paper contributes to the numerical analysis of train/track/foundation dynamics by presenting the accuracy of a coupled lumped mass (CLM) model devoted to the railway foundations and to the track/soil coupling. Following a summary of the background and the advantages of the CLM model, the coupling strategy is quantified through two application cases. Firstly, the dynamic track deflection is calculated for different railway lines considering various degrees of complexities of foundations. Then, the foundation responses are compared depending on whether detailed coupling is introduced or not. The benefit of the proposed model is emphasized by presenting free-field ground vibration responses generated by a tram and a high-speed train, obtained by a revisited two-step prediction model developed by the authors.