The tractor and semitrailer routing problem with many-to-many demand considering carbon dioxide emissions

The tractor and semitrailer routing problem with many-to-many demand (TSRP-MMD) is investigated in this study. The TSRP-MMD extends the existing studies on the rollon–rolloff vehicle routing problem (RRVRP) to a many-to-many problem with an intercity line-haul network background. To demonstrate and utilize the energy efficiency of the tractor and semitrailer combination, the TSRP-MMD takes carbon dioxide (CO₂) emissions per ton-kilometer as the objective. Because the problem is NP-hard, a modified Clarke and Wright Savings heuristic algorithm (CW) followed by an improvement phase and a local search phase is developed to solve the TSRP-MMD. The integer program is used to find optimum solutions for small-scale problems. The computational results show that the developed heuristics can be efficiently used to solve the problem.     

混凝土冬季施工的质量问题及应对措施

混凝土工程进入冬季施工时,只要采用适当的施工方法,避免新浇筑混凝土早期浸冻,使外露混凝土与冬季气温保持较小温差,就可以减少一些施工中可能出现的问题。介绍混凝土冬季施工的质量问题及应对措施,可为同类工程提供一定的参考。     

高职服务类专业普通话训练存在问题及对策研究——以辽宁现代服务职业技术学院为例

高等职业院校承担着理论教学与职业教育的双重任务,而在服务类专业的人才培养过程中,如何提高服务质量成为了高职服务类专业办学核心竞争力的重中之重。在提高服务质量的要求中,首当其冲就是语言的沟通,由此,普通话的训练就显得尤为重要。但是,在现今高职服务类专业教学的过程中,语文教学被划在公共课的范围内,与专业教学隔离开来,且并不被专业教学所重视,导致在普通话训练过程中出现了一系列问题。那么,高职服务类专业普通话训练存在哪些问题,如何去解决呢?本文将以辽宁现代服务职业技术学院(简称"辽服职院")为例进行论述。     

Model and algorithm for container ship stowage planning based on bin-packing problem

In a general case, container ship serves many different ports on each voyage. A stowage planning for container ship made at one port must take account of the influence on subsequent ports. So the complexity of stowage planning problem increases due to its multi-ports nature. This problem is NP-hard problem. In order to reduce the computational complexity, the problem is decomposed into two sub-problems in this paper. First, container ship stowage problem （CSSP） is regarded as “packing problem”, ship-bays on the board of vessel are regarded as bins, the number of slots at each bay are taken as capacities of bins, and containers with different characteristics （homogeneous containers group） are treated as items packed. At this stage, there are two objective functions, one is to minimize the number of bays packed by containers and the other is to minimize the number of overstows. Secondly, containers assigned to each bays at first stage are allocate to special slot, the objective functions are to minimize the metacentric height, heel and overstows. The taboo search heuristics algorithm are used to solve the subproblem. The main focus of this paper is on the first subproblem. A case certifies the feasibility of the model and algorithm.     

基于MATLAB的混合型蚁群算法求解旅行商问题

蚁群算法是受自然界中蚁群搜索食物行为启发而提出的一种智能优化算法,通过介绍蚁群觅食过程中基于信息素的最短路径的搜索策略,给出基于MATLAB的蚁群算法在旅行商问题中的应用,针对蚁群算法存在的过早收敛问题,加入2-opt方法对问题求解进行局部优化.计算机仿真结果表明,这种混合型蚁群算法对求解旅行商问题有较好的改进效果.     

Global optimization method for network design problem with stochastic user equilibrium

In this paper, we consider the continuous road network design problem with stochastic user equilibrium constraint that aims to optimize the network performance via road capacity expansion. The network flow pattern is subject to stochastic user equilibrium, specifically, the logit route choice model. The resulting formulation, a nonlinear nonconvex programming problem, is firstly transformed into a nonlinear program with only logarithmic functions as nonlinear terms, for which a tight linear programming relaxation is derived by using an outer-approximation technique. The linear programming relaxation is then embedded within a global optimization solution algorithm based on range reduction technique, and the proposed approach is proved to converge to a global optimum.     

基于图论的物流配送线路问题研究

以连锁企业城市配送中心辐射范围内的三级物流配送为研究问题,通过分析旅行商问题与哈密尔顿回路的对应性,在证明哈密尔顿回路存在性的基础上,应用图论优化方法获得满足最小费用流的哈密尔顿回路,从而求解城市配送系统范畴内的区域配送线路问题。通过实例分析,该方法在求解此类问题的可行性和优越性得到了验证。     

城市步行品质交通改善设计研究

首先整合与步行品质改善相关的理论，提出“以人为本”的九项设计理念，并依据实施的迫切程度和困难程度将步行品质交通改善设计理念重新组织并划分为三个层次：必要的理念、非常可取的理念和不错的附加理念，以利于指导实践。然后构建“以问题为导向”的研究框架，将步行品质改善这一复杂问题简化为多个简单问题，并充分吸收已有的知识成果以寻求解决之道。最后提出步行品质交通改善设计的技术建议：完善步行网络、优化步行设施和提升步行环境。     

一种基于共轭梯度法的动态载荷识别方法

在载荷识别过程中,由于噪声和结构矩阵病态的问题,对测量的响应数据有影响.本文运用共轭梯度法最优化方法,来解决多源动态载荷识别中的不适定问题.将该方法应用在加筋板模型和平面桁架结构上进行数值仿真,仿真算例结果表明所提出的载荷识别方法在测量位移响应数据含有5％的噪声水平下,有效地得到稳定近似解,实现了载荷识别.该方法抗噪能力强,有效解决反问题的不适定性.     

云浮市区典型交叉口通病诊断

结合云浮市区典型交叉口现状,剖析通病所在,从技术和管理层面提出症结的解决方案,可供相关技术人员参考和借鉴.