我国航空旅客运输需求预测——基于计量经济学与系统动力学组合模型

航空运输需求预测是民航发展规划和决策的前提,预测结果的精度会对民航的发展产生重要的影响.基于系统动力学原理构建了民航客运需求系统的因果关系图,分析了各因素间的因果关系,在此基础上,建立了航空客运需求的系统动力学模型,并引入了计量经济学来建立模型的数学方程.然后,对模型进行了有效性检验,结果显示建立的模型可以较好地反映民航客运的实际需求,证明了模型的有效性.最后,应用该模型对我国未来几年的航空客运需求进行了预测,并对比了不同的预测情景,结果显示经济水平对航空客运需求影响显著,宽松的人口政策在一定程度上会降低航空客运需求.     

Reliability Prediction Method Based on State Space Model for Rolling Element Bearing

Reliability analysis based on equipment’s performance degradation characteristics is one of the significant research areas in reliability research. Nowadays, many researches are carried on multi-sample analysis. But it is limited for a single equipment reliability prediction. Therefore, the method of reliability prediction based on state space model(SSM) is proposed in this research. Feature energy of the monitored signals is extracted with the wavelet packet analysis and the associated frequency band energy with online monitored data. Then,degradation feature is improved by moving average filtering processing taken as input pair model parameter of SSM to be estimated. In the end, state space predicting model of degradation index is established. The probability density distribution of the degradation index is predicted, and the degree of reliability is calculated. A real testing example of bearing is used to demonstrate the rationality and effectiveness of this method. It is a useful method for single sample reliability prediction.     

基于遗传BP网络的城市空气质量等级预测

针对空气污染诱因复杂、影响机理非线性等特点,选用遗传BP网络,对城市空气质量等级进行短期预测.分别使用2类共10种方案对数据进行了关联,使用遗传算法对输入变量进行了筛选,对BP网络的网络结构、权值和阀值进行了优化.仿真结果表明,经优化后的BP网络对未来8天空气质量等级的平均预测正确率达67.1%.     

回转体艇型阻力近似计算方法与试验研究

研究了试验设计和近似模型技术,确定了回转体艇型曲线的6个控制参数,根据系列回转体阻力数值计算结果,建立了水下航行器阻力近似计算的响应面模型及径向基神经网络模型。通过系列模型试验验证了多种近似模型的拟合精度,与工程估算方法以及CFD方法进行了比较。结果表明,4阶响应面模型及径向基神经网络模型精度远高于工程经验公式,能够正确反映艇型参数对阻力结果的影响,为后续艇型优化设计带来一定的参考价值。     

Numerical prediction of wave-induced long-term extreme load effects in a flexible high-speed pentamaran

The theory and procedure established by Wu and Moan in 1996 and 2005 and Wu and Hermundstad in 2002 were applied to a high-speed transatlantic pentamaran containership. Nonlinear time-domain simulations of ship motions and load effects were carried out in different sea states. The simulated responses were validated against model tests with satisfactory results. The short-term probabilities of exceedance were estimated by using different stochastic analysis procedures. The long-term probabilities of exceedance were obtained based on the short-term results. These served as information about loading in a reliability-based design approach. The load effects in a semiprobabilistic design were also calculated at an appropriate probability of exceedance level.     

旅客列车在线安全状态监测及故障预警系统

列车故障是铁路行车安全的潜在威胁。文章从分析我国旅客列车的基本结构、安全装备情况入手,提出了基于TCN的旅客列车在线安全状态监测及故障预警系统具体实现方案。     

基于断裂力学的齿轮箱螺栓的失效分析及改进研究

指出由于铝合金齿轮箱和钢制螺栓的热膨胀系数不同．在齿轮箱温度升高后产生附加的温差载荷．此温差载荷是螺栓失效的根本原因，由此依据相关公式提出了改进措施。在对联接螺栓进行受力分析的基圳上应用断裂力学理论．对改进前后螺栓的疲劳寿命进行了预测。原结构的疲劳寿命短．不满足要求．改进后的结构满足要求：改进措施是有效的，这也为齿轮箱的设计提供了参考。并对45钢和40Cr这2种材质的螺栓进行了对比．进一步说明失郊的根本原因不是材质的问题．而是温差载荷     

非均衡高速公路通行费收取预测初探

根据非均衡的相关理论及研究成果，从分析高速公路运输市场经济特性出发，在研究高速公路交通需求与供给非均衡的基础上，提出非均衡高速公路通行费收预测的思想，并对非均衡高速公路费收预测的方法进行初步探讨，可为高速公路费收预测提供一种有益的思路。     

灰色系统预测在工程材料价格中的应用

由于工程量清单计价规范的实施，企业自主报价，市场竞争形成价格的工程造价管理模式的推行已成为必然，这种计价模式对材料价格信息的需求更加及时，但由于价格信息的发布存在着滞后性，并不能满足工程投标的需要，以已知的信息价为基础，利用灰色系统理论的GM（1，1）模型预测未来几个月份的材料价格，为建设工程各方提供指导性和参考性的材料价格，并提供优质服务，满足实际需要。     

大体积混凝土裂缝控制综述

简述大体积混凝土裂缝产生的原因,裂缝预测,现场控制,材料选择,混凝土的养护。