空间天气对导航卫星的影响

简要介绍了空间天气的基本概念,对灾害性空间天气可能对导航卫星所产生的主要影响进行了探索;进而着重分析了电离层电子密度、电离层暴、电离层突然骚扰等空间天气要素对卫星导航定位系统的影响。     

Rice信道下的测向误差分析

研究Rice信道下天线阵列的相位关系模型,总结Rice因子估计的可行方法;对Rice信道下的测向误差进行了计算和仿真,在此基础上分析测向误差的统计特性,该统计特性可以用于对测向结果的可信度进行估计。     

关联理论对大学英语听力教学的启示

关联理论在英语听力教学中起着十分重要的作用:有助于对听力材料内容的预测,有助于吸收听力材料中的新信息,较好地解决了学生辨音速度慢、理解速度慢的问题。本文阐述了关联理论在英语听力教学中的实际应用。     

钢管砼偏心受压构件的徐变分析

钢管砼结构徐变由于物理状况上封闭、干硬性、养生时不浇水,受力上卸载而低于普通砼的徐变,由于徐变导致的钢管和砼的应力[1]重分布十分明显而不可忽视,为了有效计算核心砼徐变导致的重分布应力,在推导轴心受压构件徐变公式的基础上,结合大小偏心受压构件的受力特点,偏安全地考虑最大纤维处的徐变,根据弹性理论及叠加原理推导了钢管砼构件徐变系数的一般计算公式,并测试了轴心受压和偏心受压结构的徐变应变和收缩应变,经比较,徐变计算比较吻合,验证了理论分析.     

公路勘察设计阶段对工程造价的影响

论述了公路勘察设计阶段的重要性及存在的主要问题,阐述了公路勘察设计阶段对工程造价的影响。     

Convergence of Iterative Sequence with Mixed Errors for Uniformly Quasi-Lipschitzian Mappings

Introduction In1973,PetryshynandWilliamson[1]proveda sufficientandnecessaryconditionforPicarditerative sequencesandManniterativesequencestoconvergeto fixedpointsforquasi nonexpansivemappings.In1977,GhoshandDebnath[2]extendedtheresultof Ref.[1]andgavethesu…     

Multivariate assimilation in MERCATOR project: New statistical parameters from forecast error estimation

The new operational prototype of Mercator (french Global Ocean Data Assimilation Experiment contribution) is composed of a North Atlantic primitive equation ocean model OPA (Ocean Parallel Algorithm between 20°S and 70°N, [Madec, G., P. Delecluse, M. Imbard and C. Lévy (1998). OPA8.1 ocean general circulation model reference manuel. Notes du pôle de modélisation IPSL. n°11: 91p]) and of a multivariate and multidata assimilation scheme [De Mey, P. and M. Benkiran (2002). “A multivariate reduced-order optimal interpolation method and its application in Mediterranean basin-scale circulation.” Ocean Forecasting : Conceptual basis and application, Pinardi, N., Springer Verlag.] This system has already given some significant improvements from previous Mercator configurations (M. Benkiran, personal communication). However some biases on ocean state still remain in the tropics where the reduced-order optimal interpolation scheme is suspected to be ill-parameted in the model forecast error. Indeed the guess error covariance matrix is decomposed into an error variance value and a spatio-temporal correlation function which are assumed to have some “good” properties (spatial homogeneity of the correlation function, constant ratio between signal and error variance). This study shows how we can use ensemble methods to validate these assumptions. We can see that the correlation function can reach negative values locally, mostly in regions of high variability contradictory with the homogeneous hypothesis. The reduced space used in the operational configuration is based on the signal seasonal Empirical Orthogonal Functions (EOFs). An empirical relationship between signal and error variance has been set and the correlation function is the same on every dimension of the reduced space. By projection of the estimated guess error variance onto the reduced space, we find a repartition of this quantity quite different to what was set in the system. The error statistics is found to be inhomogeneous compared to hypothesis made in the assimilation scheme. These two new parameters tested separately in the assimilation scheme gives significant improvements of the forecast and analysis results. This is particularly obvious in the tropics. But relationship between signal and error statistics (as assumed in the optimal interpolation) is found to be complex.     

基于变质量热力学的油舱气相区动态模型

根据变质量系统热力学原理,基于浓度边界层理论作出油舱气相区中舱气均一性的系列假设,应用控制容积质量守恒方程、能量守恒方程和连续性方程及气体状态方程,针对液货作业建立油舱气相区数学模型。该模型普适于表征各种液货作业过程油舱中舱气组分、压力和温度等参数的变化。研究表明,气相状态受到液货作业行为及环境因素的扰动,具体行为取决于液货装卸、惰气充注、透气速率、环境温度和货物物性参数等。该研究为气相状态安全控制和液货作业优化提供了理论依据。     

大跨径连续刚构桥的随机地震动响应分析

以苏通长江大桥辅航道桥为工程背景,考虑结构自重引起几何非线性以及桩土相互影响,建立该桥的地震分析模型,分析行波效应、部分相干效应和局部场地效应对结构地震响应的影响规律。结果表明:行波效应总体上削弱结构的位移响应,对内力响应的影响较大,在相位差为1s的情况下,面内弯矩响应的增幅达到25%;局部场地效应对内力及位移响应的影响均较大;相干效应削弱桥梁主墩的弯矩响应。     

加强德育实践性的思考与探索

实践性欠缺是我国高等学校思想品德教育长期存在的一个实际问题。克服以往单纯的知识传授,增加德育的实践性环节,加强对青年学生的德育行为训练和实践磨练,是德育改革的趋向,也是增强学校德育实效性的重要途径。