汉江安康站最大径流量的动态预测模型研究

用平稳时间序列的ARMA( p ,q)模型分析法 ,分析了汉江安康站 1 943年到1 995年共 5 3年最大径流量的水文资料 ,建立了陕南汉江安康站最大径流量的中短期动态预测数学模型 .经对 1 996年和 1 997年的最大径流量进行预测 ,结果与实际相吻合     

弹性系统动力学总势能不变值原理

提出了弹性系统动力学总势能不变值原理 ,它是建立列车 -桥梁系统、列车 -轨道系统空间振动方程的关键理论 .不管动力学系统如何复杂 ,其振动方程都可由此原理及作者以前提出的“对号入座”法则简便建立 .与哈米顿原理比较 ,此原理不需要在 t1至 t2 的时间区段积分 .算例证明了此原理的正确性和有效性     

Local to unity,long‐horizon forecasting thresholds for model selection in the AR(1)

This article introduces a novel framework for analysing long‐horizon forecasting of the near non‐stationary AR(1) model. Using the local to unity specification of the autoregressive parameter, I derive the asymptotic distributions of long‐horizon forecast errors both for the unrestricted AR(1), estimated using an ordinary least squares (OLS) regression, and for the random walk (RW). I then identify functions, relating local to unity ‘drift’ to forecast horizon, such that OLS and RW forecasts share the same expected square error. OLS forecasts are preferred on one side of these ‘forecasting thresholds’, while RW forecasts are preferred on the other. In addition to explaining the relative performance of forecasts from these two models, these thresholds prove useful in developing model selection criteria that help a forecaster reduce error. Copyright © 2004 John Wiley & Sons, Ltd.     

聚硅氧烷酯类液晶(PMMS)气相色谱固定液的研究——Ⅰ.侧链为苯甲酸联苯酚酯型的PMMS

设计并合成了聚甲基硅氧烷酯(PMMS),其侧键为4-n-烷氧基联苯酚苯甲酸酯型的计8个,具类似结构侧键的计5个。合成的中间伴和产物分别由MS、NMR、IR和EAR等分析方法得到证实。并用IR谱图说明了硅氢加成反应的进行。相变温度的测定结果,表明这些PMMS大多具有较宽的液晶相温度范围(大于100℃)。毛细管气相色谱的测定表明,PMMS-AOBPAIOB既有SE-52的高柱效和热稳定性,又有BBBT的优异分离性能。PMMS-A_m~*OBPAIOB的填充柱有优异的分离选择性,可以有效地分离喳啉、异喳啉和2-甲基喳啉。表明了作为固定液,PMMS兼有硅油和液晶的特点。     

膜法水处理系统的前处理工艺设计及考虑因素

讨论了膜法水处理系统设计前处理工艺的设计选择,根据前处理的对象介绍了处理工艺和方法,提出了在工艺设计中应考虑的一些因素。     

GDP数据生成模式

从现代经济计量学的角度分析了国内生产总值(GDP)绝对数的数据生成模式及GDP指数的数据生成模式，得到GDP绝对数的对数序列是一单位根过程、GDP指数的对数序列是一稳定过程。最后，讨论了两模型间的转换。     

基于比较利益下农业生产模式的模型研究

在连续时间的假设下,研究了农业产出量服从几何布朗运动的最优控制问题。首先借助于马尔可夫过程理论确定出转移概率密度,再利用分布参数系统模型来描述某个地域的粮食和经济作物的产出量在随机变化的情况下,农业生产的分布模型。最后探讨了在均衡条件下农业生产者以寻求利益最大化为目的的最优控制方程。同时给出了某地域粮食及经济作物的产量预测分析模型。参9。     

Optimal Component Types for the Design of Construction Processes

Within the project preparation phase, experienced professionals manually map design information onto process information with the aim to develop realistic and practical schedules. Unfortunately, the mapping itself is neither part of any underlying data model nor is it supported by current scheduling tools. As a consequence the process of setting up the data model for a schedule is still not supported formally. Huhnt and Enge described a modelling technique that addresses the missing linkage between design and process information[1]. The approach makes use of so called component types. These are template sub-processes that describe the fabrication procedure of typical building components. Decomposing the building into com-ponents and assigning a component type to each component allows for formal support while scheduling. Depending on the decomposition of the building into components and the complexity of the involved component types the specification effort differs. The question about optimal component types arises: Which layout of building components and component types results in minimal specification effort? This paper presents a branch and bound algorithm to determine optimal component types. For a given schedule, which has been modelled based on component types, all possible decompositions into sub-processes are determined. During the decomposition process the encountered configurations are compared. Those with minimal specifica-tion effort are registered. Theoretical and practical examples are examined and discussed.     

局部平稳随机振动的处理和应用

本文介绍用乘积模型定义的局部平稳随机过程,乘积模型将局部平稳随机过程分成两部分,分别在时间域和频率域进行处理,并给出相应的偏度误差和统计误差。应用部分介绍局部平稳随机数据处理方法在改善潜地导弹在弹射时的振动环境和控制振动环境方面的经验。