Robust cascade control for the horizontal motion of a vehicle with single-wheel actuators

The article presents a cascade control for the horizontal motion of a vehicle with single-wheel actuators. The outer control loop for the longitudinal and lateral accelerations and the yaw rate ensures a desired vehicle motion. By a combination of state feedback control and observer-based disturbance feedforward the inner control loop robustly stabilises the rotating and steering motions of the wheels in spite of unknown frictions between tyres and ground. Since the three degrees of freedom of the horizontal motion are affected by eight tyre forces, the vehicle considered is an over-actuated system. Thus additional control objectives can be realised besides the desired motion trajectory as, for example, a maximum in driving safety. The corresponding analytical tyre force allocation also guarantees real-time capability because of its relatively low computational effort. Provided suitable fault detection and isolation are available, the proposed cascade control has the potential of fault-tolerance, because the force allocation is adaptable. Another benefit results from the modular control structure, because it allows a stepwise implementation. Besides, it only requires a small number of measurements for control purposes. These measurements are the rotational speeds and steering angles of the wheels, the longitudinal and lateral acceleration and the yaw rate of the vehicle.     

Recreational Leasing of Alaska Commercial Halibut Quota: The Early Years of the GAF Program in Alaska

The Pacific Halibut Catch Sharing Plan formalized the process for allocating halibut between the Alaska commercial and recreational charter sectors. It included a new program intended to allow for “flexibility” through inter-sectoral trading, permitting charter operators to lease commercial halibut pounds to relax client harvest restrictions. Here we evaluate the first two years of lease market activity and participation. Participation from some commercial quota holders in the lease market suggests that the program provided beneficial flexibility; in fact, the number of transfers to the charter sector was greater than transfers within the commercial sector for some quota types. We also identified a high proportion of self-leasers. However, transfers to the charter sector were on average smaller than within-sector commercial transfers, and total poundage leased by the charter sector was low compared with commercial transfers. Usage of leased quota by the recreational charter sector enables the harvest of larger fish or additional fish, and provides flexibility in catch composition on halibut closure days. Finally, the value-per-pound may be higher in the charter sector, as commercial-to-charter transfer prices approached the commercial ex-vessel price.     

舰船顶层设计指标最优分配问题计算方法

基于大型复杂工程系统设计的多学科设计优化算法,开展了舰船顶层设计指标最优分配的计算方法研究,基于协同优化算法提出了舰船顶层设计指标最优分配的一种通用算法框架。     

Schedule-based transit assignment model with vehicle capacity and seat availability

In this paper, we propose a new schedule-based equilibrium transit assignment model that differentiates the discomfort level experienced by sitting and standing passengers. The notion of seat allocation has not been considered explicitly and analytically in previous schedule-based frameworks. The model assumes that passengers use strategies when traveling from their origin to their destination. When loading a vehicle, standing on-board passengers continuing to the next station have priority to get available seats and waiting passengers are loaded on a First-Come-First-Serve (FCFS) principle. The stimulus of a standing passenger to sit increases with his/her remaining journey length and time already spent on-board. When a vehicle is full, passengers unable to board must wait for the next vehicle to arrive. The equilibrium conditions can be stated as a variational inequality involving a vector-valued function of expected strategy costs. To find a solution, we adopt the method of successive averages (MSA) that generates strategies during each iteration by solving a dynamic program. Numerical results are also reported to show the effects of our model on the travel strategies and departure time choices of passengers.     

沥青混合料汉堡车辙试验条件及评价指标研究

采用2种沥青、2种级配拌制4种混合料,分别在水浴和空气浴下进行50℃和60℃的汉堡车辙试验,分析了水和温度对车辙深度的影响;讨论了车辙深度和蠕变速率指标评价沥青混合料高温性能的不足,提出了车辙变形率指标.结果表明,水环境和提高温度都会加速车辙的产生,50℃水浴和60℃空气浴车辙深度的相关性好,50℃水浴汉堡车辙试验可以反映沥青混合料的抗车辙性能,建议B级沥青采用45℃,A级沥青采用50℃,改性沥青采用60℃的试验温度.     

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随着中国民航事业的快速发展,航班不正常变得越来越严重.虽然航空运输系统涉及空管、航空公司与机场三方面,但是目前解决不正常航班却单纯依靠空管.而这种方式无法达到减少不正常航班的目的.本文研究在协同决策机制下,航空公司自由指派航班时隙的方法问题.文中建立航班时隙指派模型,针对模型的特点设计了一种参数启发式算法。最后通过实例证明了采用本文的方法可以减少航班总延误时间并且提高航班正点率.通过该实例说明航空公司参与时隙分配决策的重要性.     

铁路枢纽内客运站分工的优化模型及算法

为了合理分配引入高速和城际客运专线的铁路枢纽内客运站的接发旅客列车任务,以始发终到客流在各客运站之间的分配、始发终到和通过客流的运行路径为决策变量,以最小化枢纽内始发终到和通过旅客的费用为目标,以客运站始发终到能力和通过能力、铁路线路旅客列车通过能力、旅客运输需求为约束条件,建立了客运站分工多目标非线性混合整数规划模型.考虑铁路枢纽内运行路径少的特点,设计了基于枚举法、多最短路和线性规划的精确求解算法.算例表明,该方法能够对3个客运站的接发旅客列车数量进行定量分配,始发终到能力占用率分别为100%、64.5%和69.3%,通过能力占用率分别为78.7%、65.9%和25%.     

基于多属性决策运输车编配方案研究

在信息化战争中,后勤运输保障举足轻重。根据部队运输需求,制定出科学合理的运输车编配结构对于提高部队公路运输保障能力具有重要的指导意义。分析了我军运输车编配存在的问题,介绍了基于最大离差化的多属性决策模型,为运输车编配方案评价提供了一种合理的研究方法。并以某摩步师直属汽车营为例,对运输车的备选方案进行了排序和选优,得到了...     

基于协同航路技术的航路资源分配方法研究

为减轻扇区拥挤,科学地利用扇区时隙资源,降低航班延误损失,本文研究了航路资源分配方法,将研究重点放到航路上,并建立了以航班总延误损失最小为目标,以扇区容量为约束的简化数学模型,该模型可以让航空公司灵活、自主地为航班确立优先等级。本文选择航班实际数据进行仿真,并使用优化软件对模型进行求解,算例仿真结果表明,所提方法能够大...