Time-domain,shallow-water hydroelastic analysis of VLFS elastically connected to the seabed

In order to ensure the safe operation of a VLFS, a combination of mooring, breakwater and other motion reducing systems is employed. In the present work, the transient hydroelastic response of a floating, thin elastic plate, elastically connected to the seabed, is examined. The plate is modelled as an Euler-Bernoulli strip, while the linearized shallow water equations are used for the hydrodynamic modelling. Elastic connectors are approximated by a series of simple spring-dashpot systems positioned along the strip. A higher order finite element scheme is employed for the calculation of the hydroelastic response of the strip-connector configuration over the shallow bathymetry. After the definition of the initial-boundary value problem, its variational form is derived and discussed. Next, on the basis of the aforementioned formulation, an energy balance expression is obtained. The effect of variable bathymetry on the response of a two connector-strip system is examined by means of three seabed profiles featuring a flat bottom, an upslope and a downslope environment. For the flat bottom case, the strip response mitigating effect exerted by the employment of two and three elastic connectors is considered. Finally, by means of the derived energy balance equation, the energy exchange is monitored, providing a valuable insight into the transient phenomena that take place in the studied configurations.     

Investigating the subjective and objective factors influencing teenagers’ school travel mode choice – An integrated choice and latent variable model

In this paper, we apply Bhat and Dubey’s (2014) new probit-kernel based Integrated Choice and Latent Variable (ICLV) model formulation to analyze children’s travel mode choice to school. The new approach offered significant advantages, as it allowed us to incorporate three latent variables with a large data sample and with 10 ordinal indicators of the latent variables, and still estimate the model without any convergence problems. The data used in the empirical analysis originates from a survey undertaken in Cyprus in 2012. The results underscore the importance of incorporating subjective attitudinal variables in school mode choice modeling. The results also emphasize the need to improve bus and walking safety, and communicate such improvements to the public, especially to girls and women and high income households. The model application also provides important information regarding the value of investing in bicycling and walking infrastructure.     

变截面高墩墩顶位移计算

由于山区的地形特点,新建高速公路存在大量高墩,墩顶位移作为设计的一项控制指标,必须进行精确验算。每个桥墩都建立模型来进行验算,计算工作量较大。通过对墩顶位移的推导提出位移计算公式,将大大的减少计算工作量,有利于提高设计效率。采用提出的计算公式与有限元模型计算结果较接近,精度较高。     

Design and development of a stated choice experiment for interdependent agents: accounting for interactions between buyers and sellers of urban freight services

Stated choice experiments have proven to be a powerful tool in eliciting preferences across a broad range of choice settings. This paper outlines the elements of a group-based experiment designed for interdependent urban freight stakeholders, along with the procedure to administer the questionnaire sequentially. The focus is on the design of a computer-assisted personal survey instrument and the value in disseminating the details of a new approach to design and collect stated choice data for interacting agents. The paper also discusses how to specify a reference alternative, and then how to recruit appropriate real-market or representative decision-making group members to participate in a subsequent phase of the survey, which incorporates the reference alternative and contextual information from an initial phase. The empirical strategy, set out in some detail, provides a new framework within which to understand more fully the role that specific attributes, such as variable user charges, influencing freight distribution chains might play, and who in the supply chain is affected by specific attributes in terms of willingness to pay for the gains in distribution efficiency.

Fixed Points and Asymptotic Properties of Neutral Stochastic Delay Differential Equations

This paper discusses a linear neutral stochastic differential equation with variable delays. By using fixed point theory, the necessary and sufficient conditions are given to ensure that the trivial solution to such an equation is pth moment asymptotically stable. These conditions do not require the boundedness of delays, nor derivation of delays. An example was also given for illustration.     

变截面车架牵引车减振器系统设计

本文介绍了变截面车架牵引车减振器系统设计分析过程,从安装方式分析、最大卸荷力计算、缸径计算、行程计算、安装角度及匹配减振器支架设计等方面进行了详细的计算分析,并对其中关键设计点进行校核分析。     

模糊聚类在交通诱导系统建设中的应用

可变情报板（交通诱导屏）在交通信息发布、交通诱导等方面起着非常重要的作用。为满足公众对交通诱导信息的需求,可变情报板的布局应得到进一步的合理规划。根据聚类分析和室外屏选址的基本原理,建立一套完整高效的室外屏选址理论,借助Excel强大的统计功能,该理论在实际工作中发挥了重要作用。     

车用柴油机可变喷嘴涡轮增压器电控系统研究

在CA6DE柴油机上,对自主开发的可变喷嘴涡轮增压器(VNT)电控系统进行了多轮匹配试验,并进行了实车道路试验,找出了CA6DE柴油机VNT电控系统的控制策略和最优MAP。在VNT电控系统中采用适合于柴油机上控制的硬件电路和PID控制算法,以达到对VNT喷嘴环开度进行精确的控制。试验结果表明,与采用普通涡轮增压器相比,采用VNT电控系统可以提高柴油机扭矩20%、降低烟度25%～50%、降低油耗5%。     

鱼雷变推力运动方程式

目前的针雷运动方程是建立在恒推力基础上的，为了将切线加速度引入弹道控制，建立变推力方程是必要的。本文以某型鱼雷及某热动力系统为对象，导出了变推力运动方程，这对鱼雷动力和控制的设计有重要的意义。