A technique for the reduction of dynamic degrees of freedom

This paper presents a variation on the component mode technique for the dynamic substructuring of large‐scale structural analysis of building and bridge frames. The principal innovation of the proposed method of dynamic reduction is that the resulting mass matrix of the reduced substructures remains diagonal. As in the component mode technique, the reduction is accomplished by transforming the degrees of freedom in the substructure using boundary shapes and internal shapes. The diagonal mass matrix is achieved by orthogonalization of the boundary shapes to the internal shapes, and a selective row‐by‐row summation of the mass matrix into the diagonal entry (where off‐diagonal terms are unavoidable). To aid in recovering the accuracy of the rigid‐body inertias that is lost in the diagonalization process, additional pseudo‐rigid‐body‐mode shapes are proposed. Copyright © 2001 John Wiley & Sons, Ltd.     

CGCS2000板块运动模型建立方法研究

使用国家级CORS站数据,建立了CGCS2000板块运动模型,该模型可以提供高精度的速度场,实现2000历元至当前历元的点位的归算。     

硫酸盐对磁赤铁矿—磁铁矿厌氧转化过程的影响

磁赤铁矿可以在厌氧微生物作用下固相转化为磁铁矿,这种转化过程具有重要的矿物学及环境磁学意义。文章通过开展硫酸盐还原菌（SRB） —磁赤铁矿交互作用实验,重点探讨了SRB 活性对磁赤铁矿—磁铁矿固相转化速率的影响。在31 d 培养期内,SO₄^2-+SRB+磁赤铁矿体系中SRB 的生长导致16.7%的SO₄^2-转化为酸可挥发性硫（AVS）,部分还原释放的Fe（II） 与AVS 反应生成单硫化物、双硫化物和多硫化物,同时铁氧化物因溶解作用粒径减小;在无SO₄^2-的SRB+磁赤铁矿体系中, SRB 还原产生的Fe （II） 主要存在于铁氧化物中,没有次生沉淀产生。X 射线衍射和穆斯堡尔谱分析结果表明在SRB 作用下纳米磁赤铁矿逐渐向磁铁矿转化,加入SO₄^2-时转化速率加快,与矿物接触的SRB 菌体的数量及其向磁赤铁矿传递电子的能力均得到了增强。在天然或人工厌氧条件下,SO₄^2-是制约磁赤铁矿向磁铁矿转化的重要因素。     

贵州省暴雨灾害分区预警业务实施探索

从贵州省暴雨灾害时空分布特点、暴雨灾害防御需求和预警发布业务发展规划,分析了在贵州省开展暴雨分区预警业务的必要性。通过分析中国暴雨分区预警业务发展现状,结合贵州省预警发布业务现状和国家突发事件预警信息发布能力提升工程（一期）建设内容,从基础数据准备、业务规范设计、系统建设、预警传播优化四个方面,探讨如何解决开展暴雨分区预警业务的技术短板,全面提升预警精细化发布能力,建立符合贵州省气象防灾减灾需求的暴雨分区预警业务体系。     

基于主动学习径向基函数的边坡系统可靠度分析

相较于极限平衡法,强度折减法在计算边坡稳定性系数上有许多优势,但更大的计算量在一定程度上限制了其在边坡可靠度分析中的应用。为了有效地减少可靠度分析中数值模型的计算次数,以减轻使用强度折减法所带来的计算压力,引入了基于主动学习径向基函数（ARBF）代理模型的高效分析方法：利用主动学习函数在极限状态面附近搜索训练样本更新代理模型,加快模型训练的收敛速度;采用线性核径向基插值函数简化模型参数优化过程,建立简洁、稳定的代理模型。此外,为了充分发挥主动学习代理模型的优势,提出针对土质边坡特性的初始采样策略。当得到稳定的代理模型后,结合蒙特卡罗模拟计算边坡的系统失稳概率。作为对比,基于两个典型边坡算例,测试了两种经典的可靠度方法：主动学习克里金模型（AK）和二次响应面法（QRSM）,论证了引入的主动学习径向基函数代理模型在计算效率上的高效性和计算模型上的稳定性。     

Deep pore water profiles reflect enhanced microbial activity towards tidal flat margins

Microbial activity in permeable tidal flat margin sediments is enhanced by two main processes. First, organic matter is supplied by rapid sedimentation at prograding tidal flat margins. Second, surface and deep pore water advection lead to a replenishment of the dissolved organic matter and sulfate pools. Increasing microbial activity towards the low water line is reflected in sulfate and methane profiles as well as in total cell numbers, sulfate reduction rates, and remineralization products. The impact of high sedimentation rates on pore water biogeochemistry is confirmed by inverse modeling reproducing the depth profiles obtained by measurements. In central parts of the tidal flats, low sedimentation rates and pore water flow velocities limit microbial activity despite the high availability of electron acceptors for microbial respiration such as sulfate. Therefore, tidal flat margins with high microbial activity are of special importance for budgeting biogeochemical cycling in tidal flat areas.     

Managing NCEA assessment practice more effectively

The National Certificate of Educational Achievement (NCEA), introduced early this decade, is the national qualification for New Zealand senior secondary school students. Commencing with Level 1 in 2002, the implementation of NCEA represented a marked change from previous norm-referenced-based qualifications and required a considerable paradigm shift in teacher assessment practice. During the transition period, learner needs often took second place to assessment in geography classrooms. This paper identifies the practices that Year 11 geography teachers used post NCEA implementation to manage assessment practice more effectively and to address the perceived over-emphasis on assessment.     

提升固定资产管理水平 保障防震减灾事业发展

加强对固定资产的管理,提高固定资产使用效益。是防震减灾事业发展的基本保障,结合山东省地震局固定资产管理工作的实践经验,提出要建立科学的管理机制和管理制度,提升固定资产管理水平,以保障防震减灾事业的健康和持续发展。     

黏性土基于强度折减法的位移土压力理论

基于强度折减法基本原理导出了考虑位移效应的黏土土压力的三种计算模式,其计算结果与离心模型试验结果都吻合较好,其中方法二不管是从理论角度还是从计算数值方面都是三者中最合理的,但是它具有一定的适用范围,适用范围为 ,也可推广至 。超出此适用范围之外时,可使用方法一和方法三进行计算。