以商圈为中心的O2O动态外卖配送路径优化模型与算法

针对线上到线下(Online to Offline,O2O) 外卖路径优化问题,综合考虑其动态配送需求、货物区分等特点以及时间窗、载货量等约束条件,将商圈看作配送中心,将快递员数量与快递员总行驶时间作为最小化目标,提出了以商圈为中心的O2O动态外卖配送路径优化模型。采用周期性处理新订单的方法将相应的快递员路径的动态调整问题转化为一系列静态TSP子问题,设计了一种分阶段启发式实时配送路径优化算法框架,并给出了一个具体算法和一个数值计算实例。在VRP通用算例的基础上,以商圈为中心生成测试算例,对本文算法进行仿真实验,并与其他算法比较。结果表明：本文算法能充分利用新订单附近的快递员进行配送,并优化其配送路径,有效减少了快递员数量与快递员总行驶时间。     

基于SD-VF理论的城市限行政策效应研究

随着我国城市化进程不断加快,城市交通供需矛盾日益突出,交通拥堵问题愈发严重,我国各地纷纷实行各种政策措施来缓解交通拥堵。本文以北京市为例,针对城市交通拥堵的现象,从系统的角度出发,运用系统动力学与灰色Verhulst预测相结合的方法(SD-VF),建立城市交通治堵模型,并采用Vensim软件对模型进行动态仿真分析,从经济、社会、环境等方面探究政策措施对城市环境生态承载力、道路生态承载力等的影响。研究结果表明,限行限号政策虽然在一定程度上提高道路生态承载力,但也可能引发“悖论”效应;修路政策并没有根本上解决城市交通拥堵问题,仅仅是把拥堵状况向后推迟;而相对于单一政策,将发展公共交通与限行政策相结合可以有效缓解交通拥堵,改善空气质量,提升环境承载力,是更加科学合理的政策措施。     

Switched safe tracking control design for unmanned autonomous helicopter with disturbances

In this paper, the switched safe tracking control scheme is investigated for the attitude and altitude system of a medium-scale unmanned autonomous helicopter with output constraints and unknown external disturbances. To keep the attitude angles and altitude within the desired constrained range, an output boundary protection approach is adopted to generate an output constrained trajectory which is piecewise differentiable. The disturbance observer-based control method is employed to handle the unknown external disturbances of the system. Because of the piecewise differentiability of the output constrained trajectory, the closed-loop error system with the safe tracking controller can be seen as a switched system with jump dynamics. The multiple Lyapunov function method is adopted to guarantee the tracking performance with designed average dwell time. Simulation results of an example are provided to illustrate the effectiveness of the proposed control scheme for the unmanned autonomous helicopter system.     

基于比值导数法的棉花蚜害无人机成像光谱监测模型研究

蚜虫是棉花的主要害虫之一,我国棉花产量每年因蚜虫危害造成的损失高达5%～10%。田块尺度的棉花蚜害空间分布监测可以辅助精准定量施药,减少环境污染。利用无人机搭载成像光谱仪获取的“图谱合一”的遥感数据因其具有分辨率高、时效性高、成本低等优势,可为作物病虫害监测提供了重要数据源。比值导数法模型简洁,运行效率高,结果精确,可以有效的应用于遥感反射率光谱解混处理,提取对目标信息较为敏感的波段,为构建虫害监测模型提供了有效的手段。因此本研究选择棉花典型生产区新疆库尔勒地区为实验区,开展以下工作: （1）以低空无人机搭载成像光谱仪获取棉花蕾期冠层成像光谱影像,结合地面调查数据,获取76个样点光谱数据及蚜害严重度(包含健康植株16个,蚜害严重度1～4级每级选取15个);(2)分析不同蚜害严重度棉花冠层光谱的特征,并利用比值导数法筛选出对蚜害胁迫敏感的光谱波段,分别为514,566和698 nm波段; (3)构建基于三个敏感波段的光谱反射率、比值导数光谱值的一元线性回归和偏最小二乘法的蚜害严重度估测模型。结果表明：(1)蚜害对棉花冠层的光谱反射率有显著影响。棉株受蚜害胁迫越严重,其在可见光区域的反射率越高,近红外波段反射率越低,发生红边区域“蓝移”;（2）比值导数法可有效提取蚜害棉花冠层光谱敏感波段,所筛选的514,566和698 nm三个波段与相关系数法所筛选的敏感波段一致;(3)利用敏感波段比值导数光谱值所构建的蚜害严重度估测模型精度优于敏感波段光谱反射率所构建的模型, 其中698 nm波段构建的模型精度最佳（R2=0.597, RMSE=0.91）; (4)三个敏感波段的比值导数光谱值所构建的偏最小二乘多元回归模型精度优于单个波段比值导数光谱值所构建的模型（R2=0.612, RMSE=0.89）;(5)基于比值导数法的棉花蚜害无人机成像光谱监测模型可以获取田块尺度的不同严重度蚜害空间分布图,对于精准定量施药有重要的指示意义。     

Laser infrared spectroscopy of vinyl fluoride in the 1280–1400 cm−1 region

The infrared spectra of CH₂=CHF have been investigated in the ν₅ and ν₆ band regions between 1280 and 1400?cm^?1, at a resolution of about 0.002?cm^?1, using a tunable diode laser spectrometer. These vibrations of symmetry species A′ give rise to a/b-hybrid bands with different contributions from both the components. Spectral analysis resulted in the identification of 1565 (J≤46, K _a ≤11) and 1651 (J≤48, K _a ≤15) transitions of the ν₅ and ν₆ fundamentals, respectively. Both bands are perturbed by the nearby states ν₈?+?ν₉ and ν₉?+?ν₁₁ through different Coriolis resonances and an anharmonic interaction. Using Watson's A-reduction Hamiltonian in the I^r representation and perturbation operators almost all the transitions have been fitted simultaneously to a model including six resonances within the tetrad ν₅/ν₆/ν₈?+?ν₉/ν₉?+?ν₁₁. A set of spectroscopic constants for the ν₅ and ν₆ bands, as well as parameters for the dark states ν₈?+?ν₉ and ν₉?+?ν₁₁ and coupling constants, have been determined. From spectral simulations the dipole moment ratio |Δμ _a /Δμ _b | was estimated to be 0.6?±?0.1 and 2.0±0.3 for the ν₅ and ν₆ bands, respectively.     

瓶颈处车辆横纵向行为建模与分析

车辆的横向偏移现象在现实的交通流中广泛存在, 交通瓶颈处的横向偏移现象往往更加显著. 车辆间横纵向的运动相互干扰, 使得瓶颈交通流组织十分混乱, 通行能力受到显著影响. 为了研究瓶颈处车辆横纵向行为规律及其对交通流的影响, 提出一个考虑横向偏移特征的车辆行为模型: 通过引入目标转向角概念,并结合经典优化速度模型, 给出了用于描述车辆的横纵向运动规律的运动方程, 同时通过分析车辆横向偏移特征, 制定了基于车辆行驶状态划分的目标转向角确定规则集. 数值模拟结果表明: 车辆的横向偏移会对交通流的运行产生影响, 在一定的横向偏移反应阈值下, 瓶颈处横向干扰于交通流的影响随着密度的增加而增加; 同时观察到了实际城市交通瓶颈的宏观及微观现象, 验证了模型的有效性. 关键词： 交通流 瓶颈 车辆行为 横向偏移特征     

Routing problems: A bibliography

This bibliography contains 500 references on four classical routing problems: the Traveling Salesman Problem, the Vehicle Routing Problem, the Chinese Postman Problem, and the Rural Postman Problem. References are presented alphabetically under a number of subheadings.     

Efficient Heuristics for the Heterogeneous Fleet Multitrip VRP with Application to a Large-Scale Real Case

The basic Vehicle Routing Problem (VRP) consists of computing a set of trips of minimum total cost, to deliver fixed amounts of goods to customers with a fleet of identical vehicles. Few papers address the case with several types of vehicles (heterogeneous fleet). Most of them assume an unlimited number of vehicles of each type, to dimension the fleet from a strategic point of view. This paper tackles the more realistic tactical or operational case, with a fixed number of vehicles of each type, and the optional possibility for each vehicle to perform several trips. It describes several heuristics, including a very efficient one that progressively merges small starting trips, while ensuring that they can be performed by the fleet. This heuristic seeks to minimize the number of required vehicles as a secondary objective. It outperforms classical VRP heuristics, can easily handle various constraints, and gives very good initial solutions for a tabu search method. The real case of a French manufacturer of furniture with 775 destination stores is presented.     

Extension of the 2-p-opt and 1-shift algorithms to the heterogeneous probabilistic traveling salesman problem

The probabilistic traveling salesman problem is a well known problem that is quite challenging to solve. It involves finding the tour with the lowest expected cost for customers that will require a visit with a given probability. There are several proposed algorithms for the homogeneous version of the problem, where all customers have identical probability of being realized. From the literature, the most successful approaches involve local search procedures, with the most famous being the 2-p-opt and 1-shift procedures proposed by Bertsimas [D.J. Bertsimas, L. Howell, Further results on the probabilistic traveling salesman problem, European Journal of Operational Research 65 (1) (1993) 68–95]. Recently, however, evidence has emerged that indicates the equations offered for these procedures are not correct, and even when corrected, the translation to the heterogeneous version of the problem is not simple. In this paper we extend the analysis and correction to the heterogeneous case. We derive new expressions for computing the cost of 2-p-opt and 1-shift local search moves, and we show that the neighborhood of a solution may be explored in O(n²) time, the same as for the homogeneous case, instead of O(n³) as first reported in the literature.     

飞机空中加油问题的研究

讨论了飞机的空中加油问题,通过比较不同方案下主机的最大作战半径,找到了辅机给主机空中加油的最佳方案,分析了存在多个基地时各基地的位置及辅机在各基地的数量,研究了二维坐标下主机的最佳飞行路径,给出了解决问题的办法.整个思路由浅入深,通过考虑辅机数目n分别为1,2,3,4的特殊情况进而探讨一般的规律,包括辅机在基地无加油时间和有加油时间以及主机在空中盘旋等不同假设条件下的复杂情况,并将统计出的数据列表对比,获得了更直观的认识.在最后进行了展望,希望结合实际中的飞机空中加油问题综合考虑风力、风向等随机因素的影响,拓展到3维空间的更复杂模型中,使飞机的空间加油问题变得更有实际意义.