基于区间摄动理论的隧道结构响应分析

基于区间摄动理论,针对隧道结构不确定量,结合基于单元的有限元方法,建立了隧道结构区间求解模型.该模型采用8节点等参元进行离散,同时考虑物理参数不确定性、材料非均质不确定性和荷载不确定性,利用区间有限元方法,对模型进行了不确定性分析,得到了隧道结构静力响应的区间范围,并将结果与ANSYS软件分析结果相对比.数值结果表明该模型在求解隧道结构不确定性问题是有效的、可行的.     

基于IAHP的低碳绿色高速公路评估研究

为准确分析绿色低碳高速公路的应用程度,基于高速公路实际的运营情况,构建区间层次模糊低碳绿色评价模型。首先引入区间层次分析法分析了绿色低碳高速公路的权重,其次利用模糊综合评价法建立绿色低碳高速公路评价模型。然后,基于运营实际从高速公路综合运营指标、能源环境指标以及养护管理指标3个方面构建了指标组成的评价体系。最后通过案例,以某段高速公路为例对其绿色低碳程度进行评价,结果显示模型能够有效地解决多属性的绿色低碳高速公路评价问题。     

《河港工程总体设计规范》中给水和排水条文存在的问题

从消防用水量、上水栓间距、设计暴雨重现期、集装箱冲洗用水量几个方面,对JTJ 212―2006《河港工程总体设计规范》存在的问题进行分析探讨,并提出修改建议。     

信号控制交叉口绿灯间隔时间的设计方法

采用停车视距原理,阐述了机动车绿灯间隔时间在信号控制交叉口的作用,提出了机动车绿灯间隔时间的计算方法,并通过1个简单算例进行说明。最后,给出了绿灯间隔时间在黄灯和全红之间的分配方式。     

A method to improve first order approximation of smoothed particle hydrodynamics

Smoothed particle hydrodynamics (SPH) is a useful meshless method. The first and second orders are the most popular derivatives of the field function in the mechanical governing equations. New methods were proposed to improve accuracy of SPH approximation by the lemma proved. The lemma describes the relationship of functions and their SPH approximation. Finally, the error comparison of SPH method with or without our improvement was carried out. Foundation item: The National Natural Science Foundation of China (No. 50778111); The Key Project of Fund of Science and Technology Development of Shanghai (No. 07JC14023)     

Analysis of handling performance based on simplified lateral vehicle dynamics

In this article, the analysis methods for vehicle handling performance are studied. Using simple models, dynamic characteristic parameters such as yaw, natural frequency, and the damping coefficient of a vehicle can be theoretically formulated. Here, the vehicle is simplified by a bicycle (single-track) model, and the tire is modeled by an equivalent cornering stiffness and first order lag. From the experimental road data, the tire model parameters (equivalent cornering stiffness and time lag constant) are extracted. These parameters are then inserted into the theoretically formulated equations of dynamic characteristic parameters. For the purpose of validating the efficiency of the suggested methods, experimental road tests (where the cars have different handling performances) are performed. The results show that vehicle handling performance can be sufficiently represented by the suggested dynamic characteristic parameters. So, it is concluded that the proposed method has practical use for the development of new cars or for the comparison of similar cars since the evaluations of the vehicle handling performance can be efficiently determined by the suggested dynamic characteristic parameters.     

机动车相位固定最小绿灯时间计算方法

面向典型的十字形信号控制交叉口,建立了具有8个机动车相位和4个行人相位的双环相位结构,采用一种半环分析方法,讨论了可能存在的相位组合方案和相位切换方案,定义了起始相位和末尾相位两种机动车相位属性,分析了相位切换过程的基本规律。建立了具有不同属性的机动车相位的固定最小绿灯时间与相位结构、行人相位绿灯时间、绿灯间隔时间的数值关系。以相位结构、最小行人过街时间和绿灯间隔时间为主要依据,离线计算得到机动车相位固定最小绿灯时间。控制时段内,自适应控制策略可以根据当前信号周期内的机动车相位属性,为其动态分配固定最小绿灯时间。算例分析表明,该方法具有较好的可操作性。     

基于三阶剪切形变理论的复合层合矩形板水下声辐射研究

以简化的三阶剪切形变理论为基础,由虚功原理建立了较厚复合层合矩形板水下振动与声辐射方程,通过Rayleigh-Ritz法求解系统方程。为了验证所给方法的正确性将计算结果与有限元法计算结果进行对比,并将三阶剪切形变理论（TSDT）所得声辐射解与一阶剪切形变理论（FSDT）计算结果进行对比,指出前者在计算复合层合板声辐射上的优势。最后通过改变杨氏模量,剪切模量,铺层厚度,纤维铺设角等参数,指出影响复合层合板声辐射的主要因素和分频段变化规律,可为水下典型结构声辐射预报和噪声控制提供参考。     

一种新的级联FFT算法

提出针对交叉项补偿的新级联FFT算法。通过交叉项补偿处理及级联FFT运算顺序的调整,解决了传统算法数据量大的问题,以及栅瓣效应的出现,同时降低了在进行大数据量FFT运算时,单次处理负荷过大的问题。该算法在雷达、声呐并行信号处理领域具有较好的应用前景,理论推导和仿真验证的结果都表明了该算法的可行性和有效性。     

Uncertainty in traffic forecasts: literature review and new results for The Netherlands

This paper provides a review of transport model applications that not only provide a central traffic forecast (or forecasts for a few scenarios), but also quantify the uncertainty in the traffic forecasts in the form of a confidence interval or related measures. Both uncertainty that results from using uncertain inputs (e.g. on income) and uncertainty in the model itself are treated. The paper goes on to describe the methods used and the results obtained for a case study in quantifying uncertainty in traffic forecasts in The Netherlands.