黑龙江省气象台新一代短期天气预报业务系统

新一代短期天气预报业务系统建立了人机交互工作平台,包括１３个子系统和子功能模块。建立了预报业务技术流程,经过１１个步骤完成一次预报制作。新系统与原来的业务运行机制和作业流程的主要区别是,所有的工作在工作平台上完成,大大提高了业务现代化水平。     

青海湖北土壤水分分布与土壤干层恢复

通过对青海湖北沙柳河镇土壤含水量的测定, 研究了该区土壤水分含量和土壤干层恢复等问题。结果表明:青海湖北沙柳河镇土壤含水量随着深度的增加而减少, 在年降水量略多于400 mm的条件下, 多数土壤干层中的水分得到了恢复, 干层消失, 少数土壤还有干层存在。在2009 年降水增多, 到2011 年土壤水分恢复深度达到了1.3 m, 2011 年土壤含水量显著高于2009 年。在年降水量为410 mm左右的条件下, 土壤干层恢复到1.3 m深度需要的时间为2 年左右。该区土壤水分运移缓慢, 干层恢复比黄土高原缓慢, 恢复的深度较小, 这主要是该区土壤冻结期较长等决定的。土壤干层中水分的恢复表明, 该区2009年以来草原土壤水分输出量略小于输入量。     

Seismic design of yielding structures on flexible foundations

This paper introduces a simple method to consider the effects of inertial soil–structure interaction (SSI) on the seismic demands of a yielding single‐degree‐of‐freedom structure. This involves idealizing the yielding soil–structure system as an effective substitute oscillator having a modified period, damping ratio, and ductility. A parametric study is conducted to obtain the ratio between the displacement ductility demand of a flexible‐base system and that of the corresponding fixed‐base system. It is shown that while additional foundation damping can reduce the overall response, the effects of SSI may also increase the ductility demand of some structures, mostly being ductile and having large structural aspect ratio, up to 15%. Finally, a design procedure is provided for incorporation of the SSI effects on structural response. Copyright © 2015 John Wiley & Sons, Ltd.     

3rd Ishihara Lecture: An investigation into why liquefaction charts work: A necessary step toward integrating the states of art and practice

This paper is a systematic effort to clarify why field liquefaction charts based on Seed and Idriss׳ Simplified Procedure work so well. This is a necessary step toward integrating the states of the art (SOA) and practice (SOP) for evaluating liquefaction and its effects. The SOA relies mostly on laboratory measurements and correlations with void ratio and relative density of the sand. The SOP is based on field measurements of penetration resistance and shear wave velocity coupled with empirical or semi-empirical correlations. This gap slows down further progress in both SOP and SOA. The paper accomplishes its objective through: a literature review of relevant aspects of the SOA including factors influencing threshold shear strain and pore pressure buildup during cyclic strain-controlled tests; a discussion of factors influencing field penetration resistance and shear wave velocity; and a discussion of the meaning of the curves in the liquefaction charts separating liquefaction from no liquefaction, helped by recent full-scale and centrifuge results. It is concluded that the charts are curves of constant cyclic strain at the lower end (V_s1<160 m/s), with this strain being about 0.03–0.05% for earthquake magnitude, M_w≈7. It is also concluded, in a more speculative way, that the curves at the upper end probably correspond to a variable increasing cyclic strain and K_o, with this upper end controlled by overconsolidated and preshaken sands, and with cyclic strains needed to cause liquefaction being as high as 0.1–0.3%. These conclusions are validated by application to case histories corresponding to M_w≈7, mostly in the San Francisco Bay Area of California during the 1989 Loma Prieta earthquake.     

基于局部单元劈裂的FEM/DEM自适应分析方法

为了模拟岩体中裂纹的萌生、扩展,Munjiza提出了有限元法/离散元法(FEM/DEM)耦合分析方法。因为裂纹是沿单元边界进行扩展的,亦即裂纹扩展具有网格依赖性,为获得较好的裂纹扩展形态,需要划分密集的初始网格。为解决上述难题,基于FEM/DEM耦合分析方法,提出了基于局部单元动态劈裂的FEM/DEM自适应分析方法,以克服裂纹扩展形态对网格的依赖性。该方法在最初建模时无需划分很密的初始网格,随着荷载的施加,对裂纹尖端附近的局部单元进行动态劈裂,为裂纹的后续扩展提供了更多可能的扩展方向,使得裂纹扩展不必沿着初始网格的单元边界扩展,即可以沿着单元内部进行扩展,裂纹扩展形态更为平滑,与实际情况更为接近。同时相对原FEM/DEM耦合分析方法一开始就划分很密的网格而言,新方法可以划分较为稀疏的初始网格,计算成本降低。最后,通过巴西劈裂算例与原FEM/DEM耦合分析方法对比,分析表明,新方法在一定程度上克服了裂纹扩展形态对初始网格的依赖性。     

数字化城市管理一体化数据建设研究——以郑州市为例

依据数字化城市管理对数据建设的要求,以及郑州市基础地理数据及城市管理数据现状情况,结合郑州市国土、规划等部门对基础地理空间数据的需求,本文提出了数字化城市管理数据建设一体化作业流程,将1∶500航测地形图、1∶1 000正射影像制作、城市部件测量、地理编码调查、以及数据综合建库等内容,按照其关联性进行流程设计和一体化实施。它充分利用了数字化航测成图、城市部件采集与建库、地理编码采集与建库在作业工序上的交互性,为较短时间内完成大范围城市基础地理空间数据、城市管理专题数据采集与建库提供了保证,满足了数字化城市管理、城市地籍测量等对基础空间数据的迫切需求。实践证明,一体化数据建设方案充分反映了数据之间的逻辑关系和共享可能性,既加快了数据建设进程、拓展了数据建设内容,同时又保证了数据建设质量,是一种可供借鉴应用的数据建设方式。     

风化壳型砂质高岭土矿床以钻代井取大样方法简介

本文仅就被第四系所覆盖、埋藏在潜水面下的风化壳型砂高岭土矿床以钻代井取大样方法简介。通过实践认为:此法特点是施工速度快、样品质量高、成本低、工作条件好,适用于风化壳型砂质高岭土矿床。     

Recursive calculation of hansen coefficients

Hansen coefficients are used in expansions of the elliptic motion. Three methods for calculating the coefficients are studied: Tisserand's method, the Von Zeipel-Andoyer (VZA) method with explicit representation of the polynomials required to compute the Hansen coefficients, and the VZA method with the values of the polynomials calculated recursively. The VZA method with explicit polynomials is by far the most rapid, but the tabulation of the polynomials only extends to 12th order in powers of the eccentricity, and unless one has access to the polynomials in machine-readable form their entry is laborious and error-prone. The recursive calculation of the VZA polynomials, needed to compute the Hansen coefficients, while slower, is faster than the calculation of the Hansen coefficients by Tisserand's method, up to 10th order in the eccentricity and is still relatively efficient for higher orders. The main advantages of the recursive calculation are the simplicity of the program and one's being able to extend the expansions to any order of the eccentricity with ease. Because FORTRAN does not implement recursive procedures, this paper used C for all of the calculations. The most important conclusion is recursion's genuine usefulness in scientific computing.