基于无人机的高层住宅最后“一百米”配送优化

针对城市高层住宅顾客对上门配送服务的需求，借助无人机停放平台，考虑包裹异质性以及无人机在不同配送阶段的精确能耗，构建以无人机飞行成本和能耗成本最小为目标，以无人机容量、电池组容量等为约束的高层住宅无人机上门配送模型，解决“垂直位置最后一百米配送”问题。基于此模型，设计带变邻域下降(VND)搜索的混合蚁群算法(HACO-VND)，引入4个算子进行变邻域下降搜索，为了提高算法的求解性能，提出两种局部搜索算子组合，根据顾客点数量使用不同的算子组合。实验结果表明，HACO-VND算法较CPLEX在求解精度与求解时间方面更优，特别是在大中型算例中表现出较佳性能。参数分析表明，高层住宅楼层数越多，无人机单次 飞行的能耗利用率越大，无人机容量与电池组容量共同对配送方案产生影响。为以后无人机送货上门服务方面的研究提供参考和思路。     

Integrated models of land use and transportation for the autonomous vehicle revolution

ABSTRACT

The advent of the autonomous vehicle (AV) will affect not only the transportation system, but also future patterns of land development. Integrated land use and transportation models will be critical tools in assessing the path forward with this technology. Key questions with respect to land use impacts of AVs arise from potential changes in sensitivity to travel and reduced demand for parking. It is an open question whether AVs will induce urban sprawl, or whether spatial economies of agglomeration will mitigate any reductions in travel time sensitivity. The deployment of shared fleets of AVs would likely reduce parking demand, producing yet to be explored impacts on property development within existing urban footprints. We perform a critical assessment of currently operational models and their ability to represent the adoption of AVs. We identify the representation of time in such models as a vital component requiring additional development to model this new technology. Existing model applications have focused on the discrete addition of new infrastructure or policy at a fixed point in time, whereas AV adoption will occur incrementally through time. Stated adaptation surveys are recommended as tools to quantify preferences and develop relevant model inputs. It is argued that existing models that assume comparatively static equilibrium have been convenient in the past, but are insufficient to model technology adoption. In contrast, dynamic model frameworks lack sufficient structure to maintain reasonability under large perturbations from base conditions. The ongoing advancement of computing has allowed models to move away from being mechanistic aggregate tools, towards behaviourally rich depictions of individual persons and firms. However, much work remains to move from projections of existing conditions into the future, to the evolution of the spatial economy as it evolves through time in response to new technologies and exogenous stresses. Principles from complex and evolutionary systems theory will be important in the development of models with the capacity to consider such dynamics.     

汽车车身计算机辅助设计系统的集成环境

本文分析了计算机辅助车身设计的特点，指出必须集成的观战构建车身ＣＡＤ系统，并给出了一车身身ＣＡＤ系统集成环境的组织结构。     

机车车辆动力学研究及发展

机车车辆动力学在最近10年得到迅速发展,考虑车辆—轨道耦合作用的耦合模型得到广泛应用。随着大跨距跨江铁路桥的建设,车和桥的耦合振动会引起接触网的振动,进而影响弓网的耦合振动。因此十分有必要开展接触网—受电弓—机车车辆—线路—桥梁耦合大系统动力学的研究。进行机车车辆动力学性能优化,必须首先确定机车车辆动力学三要素的优先关系,即运行的稳定性—安全性—平稳性,建立以列车为研究对象的模型,同时在模型中考虑机车车辆结构弹性和频变特征悬挂参数以及气流扰动的影响,进而进行灵敏度分析和参数优化。给出考虑频变特性的钢弹簧等效计算方法以及基于循环变量的列车系统动力学建模和计算方法,并验证了计算方法的有效性。     

单频GPS进行高精度线路测量和有轨车辆定位的有效方法

轨道线路测量和有轨车辆的定位常采用GPS定位技术。利用GPS单频接收机实现高精度快速定位的关键是提高GPS单频相位模糊度解算的效率和成功率。基于轨道线路垂直方向变化不大和有轨车辆沿一定线路行驶的特点,提出一种有效的单频相位模糊度解算方法。对GPS单频接收机提供的定位观测值进行粗差探测、修正和剔除等数据预处理,用低噪声和低多路径效应的载波相位观测值对码伪距观测值进行平滑处理,再用附加约束的方法估计双差模糊度实数解,以此为基础进行模糊度搜索固定。算例显示,该方法可提高模糊度实数解估计的精度和可靠性,缩小模糊度的搜索空间,使模糊度解算效率和成功率得到提高,有利于单频GPS接收机在高精度的线路测量和有轨车辆的定位中得到更广泛的应用。     

Development of Green-Naghdi models with a wave-absorbing beach for nonlinear, irregular wave propagation

Two-dimensional and three-dimensional Green-Naghdi (GN) models equipped with a numerical wave-absorbing beach have been developed to simulate nonlinear, regular, and irregular wave propagation. The numerical beach is introduced near the downstream boundary to absorb outgoing waves. An appropriate amount of numerical damping and an appropriate length of numerical beach are investigated using numerical experiments. The results show that the GN models with a numerical beach work very well in simulating wave propagation in water in a small computational domain.     

长江干线航道条件与船舶定线制问题分析与研究

通过分析长江干线已实施船舶定线制的特点,分析船舶定线制的一般形式与通航条件,提出了长江干线船舶定线制的航道尺度计算方法和水流条件指标,并结合航道条件,提出了长江干线其他未实施船舶定线制河段的定线制形式,为进一步完善内河船舶定线制提供了一种方法和思路。     

用动态规划方法优化设计船舶车辆甲板结构

基于规范的车辆甲板结构优化设计在数学上是一个较大的非线性规划问题，而且为了满足实际需要，其中一些变量只能离散变化。本文将该问题处理为三阶段决策问题，因而能运用动态规划方法有效地求解。通过一个实例详细说明求解过程，从中看出应用动态规划方法解决基于规范的船舶结构优化设计问题的特色。     

The design of bus route systems — An interactive location-allocation approach

An interactive modelling approach is developed to solve the practical problem of bus route network design. Possible bus routes are identified with facilities which can be located. Zones or pairs of zones in the urban area are identified with customers who will be allocated to the established facilities. It is shown that the classical Set Covering Problem is useful under the assumption of fixed demand; the Simple Plant Location Problem is effective under the assumption of demand which is sensitive to the level of bus service provided.     

肩回交路条件下多机牵引机车周转图的优化

针对采用机车肩回交路的重载铁路线路,将其列车运行图中的列车运行线转化为节点,机车周转线转化为边,运用机车转化为流,从而将机车周转图的优化问题转化为网络流问题.在此基础上,以运用机车数最少、单机走行数最少、附挂机车数最少、机车在站停留时间最短和机车工作均衡性最好为优化目标,以网络流问题中的节点流量守恒和节点流量要满足节点需求为约束条件,建立肩回交路条件下的多机牵引机车周转图多目标优化模型.按照优化目标函数的优先级,采用分层序列法对模型求解,并利用C#语言编写程序,通过调用ILOG CPLEX优化软件实现了该算法.算例表明,采用所给模型和据此编制的机车周转图优化程序,可以快速优化肩回交路条件下的多机牵引机车周转图.