Tractor–semitrailer model for vehicles carrying liquids

This article presents a model for solving solid–fluid interactions in vehicles carrying liquids. A tractor–semitrailer model is developed by incorporating suspension systems and tire dynamics. Owing to the solid–fluid interaction, equations of motion for the vehicle system are coupled. To simplify the complicated solution procedure, the coupled equations are solved separately using two different codes. Each code is analyzed separately; but as the parameters of the two codes depend on each other, the codes must be connected at the end of each time step. To determine the dynamic behavior of the system, different braking moments are applied. As the braking moments increase, braking time decreases. However, it turns out that increasing the braking moment to more than a certain level produces no significant results. It is also shown that vehicles carrying fluids need a greater amount of braking moments in comparison to vehicles carrying solids during braking. In addition, as the level of the fluid inside the tanker increases, from one-third to two-third of the tanker’s volume, the sloshing forces applied to the tanker’s walls increase. It was also concluded that the strategy used in this article to solve for the solid–fluid interaction by incorporating vehicle dynamic effects represents an effective method for determining the dynamic behavior of vehicles carrying fluids in other critical maneuvers.     

在道路交通和城市化进程影响下对汽车销量的预测

本文研究了汽车销量在道路交通和城市化进程影响下的预测模型的建立,以历史数据为检测依据,判断所建模型的可行性,并对2011~2015年末汽车总销量进行了预测。其模型参数即道路交通和城市化进程对汽车销量的影响因素包括城镇人口数、城镇居民人均可支配收入、城市化率、城市年末实有道路长度、城市年末实有道路面积、公路里程。经精度检验,BP神经网络可用于预测城镇人口数、城镇居民人均可支配收入、城市化率、公路里程。二元线性回归可用于预测城市道路长度和城市道路面积。最后BP神经网络利用其在处理非线性系统方面的优越性,实现在各参数影响输入下对汽车总销量输出的任意非线性映射且具有较高的预测精度。     

分段施工PC梁桥线形的分形预测方法

充分考虑到分段施工PC梁桥施工阶段线形变化的非线形,复杂性和随机性,提出一种基于分形理论的节段线形预测方法。采用滚动选取预测样本降低原始误差累计的方法,建立了节段施工线形预测理论模型。将此模型应用于黄河大桥悬臂施工线形预测控制中,按节段施工周期依次预测下一节段的线形指标,结果证实了分段施工PC梁桥线形变化的分形特征,与实测和理论值相比,预测值具有较高的工程精度。     

基于前向线性预测和小波的FOG信号降噪算法研究

针对光纤陀螺输出信号的噪声,提出了一种处理该噪声的前向线性预测滤波与小波变换相结合的级联滤波方法,以前向线性预测滤波作为前段滤波器,采用DB4小波函数的强制阈值小波变换作为第二级滤波器。运用Allan方差法对级联滤波结果进行了分析,结果表明该级联滤波能取得较好的光纤陀螺信号降噪效果。     

高阶线性跟踪微分器性能研究

简要介绍了经典跟踪微分器的基本原理,在此基础上提出一种改进的高阶线性跟踪微分器。该跟踪微分器具有良好的动态响应和较强的滤波能力,兼顾了快速性和准确性的要求,可实现任意信号的跟踪和微分。该跟踪微分器形式简单、易于实现,具有优良的性能。     

基于谱图-Radon-二维小波变换方法

线性调频信号已经得到广泛的应用,通过谱图-Radon变换可以有效的检测线性调频信号的参数,但是当信噪比过低时,使用谱图-Radon变换就很难有效检测线性调频信号的参数,为此提出了基于谱图-Radon变换-二维小波变换的线性调频信号检测方法,仿真实验表明该方法能在低信噪比情况下检测出线性调频信号所对应的峰值。     

经过海峡的双层流体由底部波动产生的斜向波散射问题研究(英文)

The problem of oblique wave(internal wave) propagation over a small deformation in a channel flow consisting of two layers was considered.The upper fluid was assumed to be bounded above by a rigid lid,which is an approximation for the free surface,and the lower one was bounded below by an impermeable bottom surface having a small deformation;the channel was unbounded in the horizontal directions.Assuming irrotational motion,the perturbation technique was employed to calculate the first-order corrections of the velocity potential in the two fluids by using Green’s integral theorem suitably with the introduction of appropriate Green’s functions.Those functions help in calculating the reflection and transmission coefficients in terms of integrals involving the shape function representing the bottom deformation.Three-dimensional linear water wave theory was utilized for formulating the relevant boundary value problem.Two special examples of bottom deformation were considered to validate the results.Consideration of a patch of sinusoidal ripples(having the same wave number) shows that the reflection coefficient is an oscillatory function of the ratio of twice the x-component of the wave number to the ripple wave number.When this ratio approaches one,the theory predicts a resonant interaction between the bed and the interface,and the reflection coefficient becomes a multiple of the number of ripples.High reflection of incident wave energy occurs if this number is large.Similar results were observed for a patch of sinusoidal ripples having different wave numbers.It was also observed that for small angles of incidence,the reflected energy is greater compared to other angles of incidence up to.These theoretical observations are supported by graphical results.     

回归诊断中数据集对各点拟合值的影响分布

本文讨论了回归诊断中用于判别强影响点的各种影响函数以及它们相互之间的关系,给出了数据集对各点拟合值的影响分布,它可以作为判别强影响点的又一度量工具。最后建立了影响分布与复相关系数的联系并在多元线性模型的回归诊断中推广了这些结果。     

直线电机地铁列车牵引计算软件的开发

分析了直线电机列车牵引计算的基本方法,比较了柔性多质点和刚性多质点模型的不同,利用刚性多质点模型编制了牵引计算软件。以广州地铁四号线直线电机列车为例进行了算例分析。     

接触网全补偿链形悬挂5跨锚段关节过渡跨吊弦计算模型的探讨

通过引入当量线密度的概念,建立了接触网全补偿弹性链形悬挂及全补偿简单链形悬挂的5跨锚段关节屋脊过渡跨吊弦的计算模型