力学-经验路面设计指南（MEPDG）简介

主要介绍美国力学一经验路面设计指南（MEPDG）的背景、设计主要步骤、输入参数、材料特性、柔性路面分析和性能预测及MEPDG推广应用,可为道路工程人员参考和借鉴。     

Variational principle for determining the unknown wetted surface of a planing ship

A variational principle is presented to solve the problem of determining the unknown wetted surface of a planing ship on still water under gravity. The functional associated with the variational principle is expressed by the unknown wetted length distribution, the vortex line function, and the circulation distribution around the longitudinal sections, not by the bottom pressure distribution. In addition, the variational principle is adjoined with pseudoflow, here called reverse flow. The extremal of the functional satisfy the hull boundary integral equation in a similar way to that of lifting-surface theory and the elevated water surface condition along the spray root line. Both are sufficient to determine the wetted surface. A method of high aspect ratio approximation is also investigated. A simple relation is obtained between the wetted surface when moving and at standstill. The calculated shapes of the wetted surface of a planing plate agreed well with experimental results. Received for publication on Nov. 11, 1999; accepted on April 4, 2000     

Learning tracking controllers under unknown disturbances for the installation of rigid and flexible structures

During the installation operations of underwater structures, offshore structures such as semisubmersibles, the steady nonlinear hydrodynamic force due to the ocean current, the tidal current, and the hydrodynamic interaction between structures are regarded as major disturbances. Generally, it is difficult and very expensive to collect information about these disturbances in advance, although such knowledge would be important and necessary for precise installation. Because of this situation, we have proposed a learning tracking controller (LTC) for automated tracking/docking operations of offshore structures. The LTC can be operated without any information about current, and can be applied to the installation problem of flexible structures whose flexibility cannot be ignored. In order to confirm the effectiveness of the LTC, basin tests were carried out using experimental models with an unknown current. Two types of basin experiment were executed using an ultrasound ranging system and thrusters. One was trajectory tracking of a semisubmersible, and the other was the precise mating of flexible underwater structures. In both cases the LTC showed good performance, and in the latter case in particular, two flexible models were successfully made to track the given trajectory and dock to the docking targets with an accuracy of ±5 mm, after the trajectory had been tracked six to seven times for learning purposes. No elastic responses were excited in the flexible model. Received for publication on Dec. 1, 1999; accepted on March 13, 2000     

盾构施工有毒或可燃气体"不明"来源的探究

通过采集盾构机大轴承中的润滑油、滚刀轴承中的润滑油、盾尾密封油脂、聚氨酯及岩心样品进行试验,说明油脂会裂解为有毒、可燃气体.盾构机密封舱中的所谓不明气体,实际上是在复合地层盾构施工过程中油脂的裂解产物.     

Real-time estimation of the road bank and grade angles with unknown input observers

This paper proposes an approach for the estimation of the road angles independent from the road friction conditions. The method employs unknown input observers on the roll and pitch dynamics of the vehicle. The correlation between the road angle rates and the pitch/roll rates of the vehicle is also investigated to increase the accuracy. Dynamic fault thresholds are implemented in the algorithm to ensure reliable estimation of the vehicle body and road angles. Performance of the proposed approach in reliable estimation of the road angles is experimentally demonstrated through vehicle road tests. Road test experiments include various driving scenarios on different road conditions to thoroughly validate the proposed approach.     

未知参数的舰船辐射噪声线谱Duffing振子检测方法

当被动声呐探测舰船目标时,舰船辐射噪声中的线谱成分是舰船分类识别及航行状态监测的特征参量,通常情况下线谱的频率及数量是未知的。针对现有未知频率的Duffing振子检测方法存在系统结构复杂,判别时间长,需要人为参与等问题,本文构造了变参数单一Duffing振子检测模型,并提出了变频频率切片小波变换的Duffing振子检测方法。该方法通过设置合理的频率灵敏度参数自动地调整系统内置策动力频率值,利用频率切片小波变换提升系统抗噪性能,结合Poincare映射特征函数的系统相态定量判决方法,变频搜索待测信号中的线谱分量。在实测数据的分析处理中,对不同观测时间内的数据进行检测,实现了线谱成分的检测跟踪与频率估计,并根据时间轨迹上的频率识别信息确定存在的稳定线谱成分。数据处理结果表明,该方法能够实现低信噪比下参数未知线谱的检测与频率估计。     

Vehicle longitudinal velocity estimation during the braking process using unknown input Kalman filter

In this paper, vehicle longitudinal velocity during the braking process is estimated by measuring the wheels speed. Here, a new algorithm based on the unknown input Kalman filter is developed to estimate the vehicle longitudinal velocity with a minimum mean square error and without using the value of braking torque in the estimation procedure. The stability and convergence of the filter are analysed and proved. Effectiveness of the method is shown by designing a real experiment and comparing the estimation result with actual longitudinal velocity computing from a three-axis accelerometer output.     

基于UIO的摆式列车倾摆控制系统执行机构的故障检测

提出了一种利用未知输入观测吕（ＵＩＯ）对摆式列车倾摆控制系统执行机构进行故障检测的方法。该方法是干扰解耦原理的一个应用,通过一个全阶未知输入观测器使残差对未知输入不敏感,而对故障敏感,通过一个简单阈值逻辑来检测故障,通过计算机仿真证明了该方法的有效性。     

水声MIMO-OFDM通信系统中基于导频的信道估计算法研究

正交频分复用(OFDM)和多输入多输出(MIMO)的结合可以有效地对抗多径衰落和码间干扰,大幅度提高水声通信系统的信道容量和传输效率,在高速水声通信中有着重要的发展前景。在分析梳状导频水声MIMO-OFDM通信原理的基础上,结合水声通信及信道传播特点,建立了信道模型,研究水声MIMO-OFDM系统中的信道估计原理和LS(最小平方误差)、MMSE(最小均方误差)算法。通过仿真试验比较两种算法在信道估计中的性能差异,为实际系统设计提供了理论参考。     

Vehicle dynamics and road curvature estimation for lane departure warning system using robust fuzzy observers: experimental validation

This paper describes a new approach to estimate vehicle dynamics and the road curvature in order to detect vehicle lane departures. This method has been evaluated through an experimental set-up using a real test vehicle equipped with the RT2500 inertial measurement unit. Based on a robust unknown input fuzzy observer, the road curvature is estimated and compared to the vehicle trajectory curvature. The difference between the two curvatures is used by the proposed lane departure detection algorithm as the first driving risk indicator. To reduce false alarms and take into account driver corrections, a second driving risk indicator based on the steering dynamics is considered. The vehicle nonlinear model is deduced from the vehicle lateral dynamics and road geometry and then represented by an uncertain Takagi–Sugeno fuzzy model. Taking into account the unmeasured variables, an unknown input fuzzy observer is proposed. Synthesis conditions of the proposed fuzzy observer are formulated in terms of linear matrix inequalities using the Lyapunov method.