Single liner shipping service design

The design of container shipping networks is an important logistics problem, involving assets and operational costs measured in billions of dollars. To guide the optimal deployment of the ships, a single vessel round trip is considered by minimizing operational costs and flowing the best paying demand under commercially driven constraints. This paper introduces the Single Liner Shipping Service Design Problem. Arc-flow and path-flow models are presented using state-of-the-art elements from the wide literature on pickup and delivery problems. A Branch-and-Cut-and-Price algorithm is proposed, and implementation details are discussed. The algorithm can solve instances with up to 25 ports to optimality, a very promising result as real-world vessel roundtrips seldom involve more than 20 ports.     

Liner services network design and fleet deployment with empty container repositioning

Transportation demand of shipping container fluctuates due to the seasonality of international trade, thus, every 3–6 months, the liner company has to alter its current liner shipping service network, redeploy ships and design cargo routes with the objective of minimizing the total cost. To solve the problem, the paper presents a mixed integer linear program model. The proposed model incorporates several relevant constraints, such as weekly frequency, the transshipment of cargo between two or more service routes, and transport time. Extensive numerical experiments based on realistic date of Asia–Europe–Oceania shipping operations show that the proposed model can solve real-case problems efficiently by CPLEX. The results demonstrate that the model can reduce ship’s capacity consumption and raise ships’ capacity utilization.     

Single string planning problem arising in liner shipping industries: A heuristic approach

We propose an efficient heuristic approach for solving instances of the Single String Planning Problem (SSPP) arising in the liner shipping industry. In the SSPP a Liner Service Provider (LSP) only revises one of its many operational strings, and it is assumed that the other strings are unchangeable. A string is a service route composed of a sequence of port calls—a call is a visit to a port followed by loading/unloading operations made by a vessel. In a string the vessel's round trip terminates at the same port that it started from, and the port calls follow a published itinerary. The SSPP is regularly encountered by all LSPs, and a major part of their seasonal network planning process is devoted to repeatedly solving SSPP for different regions using experts' knowledge. Despite the practical importance of the problem, very little has been written about it in the literature. A revision is carried out in the form of a controlled re-sequencing, insertion and elimination of ports from along the current string, given a set of ports limited to those that exist on the string and a set of potential ones. The outcome determines the required capacity, service level (frequency), call sequence, etc., corresponding to the LSP's seasonal strategy. Exact decomposition methods are limited and can solve only very small size instances—small in terms of the number of ports, vessel classes, vessel number and commodities. In contrast, the proposed heuristic method is an efficient approach for obtaining high quality and practical solutions to real-size instances in significantly less computational time.     

基于复杂网络的全球海运网络脆弱性分析

全球海运网络在世界进出口贸易中具有重要的作用,其脆弱性直接影响到各国间航运贸易,对海运网络和港口的脆弱度进行研究具有重要的意义。首先,运用复杂网络的理论和方法探究了全球海运网络的拓扑结构特征;然后,结合全球海运网络的结构特性从关键节点识别和全局脆弱性两个方面分析了海运网络的脆弱性。利用MATLAB编程分析、计算了各港口脆弱度和在两种不同攻击模式下的全球海运网络脆弱度变化。结果表明,蓄意攻击的网络效率下降速度更快,即全球集装箱海运网络在面对蓄意攻击时表现出的脆弱性较大,对脆弱度较高的港口应加强预防。     

Transit network design by Bee Colony Optimization

The transit network design problem is one of the most significant problems faced by transit operators and city authorities in the world. This transportation planning problem belongs to the class of difficult combinatorial optimization problem, whose optimal solution is difficult to discover. The paper develops a Swarm Intelligence (SI) based model for the transit network design problem. When designing the transit network, we try to maximize the number of satisfied passengers, to minimize the total number of transfers, and to minimize the total travel time of all served passengers. Our approach to the transit network design problem is based on the Bee Colony Optimization (BCO) metaheuristics. The BCO algorithm is a stochastic, random-search technique that belongs to the class of population-based algorithms. This technique uses a similarity among the way in which bees in nature look for food, and the way in which optimization algorithms search for an optimum of a combinatorial optimization problem. The numerical experiments are performed on known benchmark problems. We clearly show that our approach, based on the BCO algorithm, is competitive with other approaches in the literature, and it can generate high-quality solutions.     

A simultaneous transit network design and frequency setting: Computing with bees

The transit network design problem belongs to the class of hard combinatorial optimization problem, whose optimal solution is not easy to find out. We consider in this paper the transit network design problem in a way that we simultaneously determine the links to be included in the transit network, assemble chosen links into bus routes, and determine bus frequency on each of the designed routes. Our approach to the transit network design problem is based on the Bee Colony Optimization (BCO) metaheuristic. The BCO algorithm is a stochastic, random-search technique that belongs to the class of population-based algorithms. This technique uses a similarity among the way in which bees in nature look for food, and the way in which optimization algorithms search for an optimum of a combinatorial optimization problem. The numerical experiments are performed on known benchmark problems. We clearly show that our approach, based on the BCO algorithm is competitive with the other approaches in the literature and that can generate high-quality solutions.     

A route set construction algorithm for the transit network design problem

The transit network design problem (TNDP) aims to determine a set of bus routes for a public transportation system, which must be convenient from the viewpoints of both users (people who use public transportation) and operators (companies who own the resources to give the service). This article presents a constructive algorithm for the TNDP. It is specially designed to produce a set of routes that fulfils demand covering constraints, while taking into account the interests of both users and operators. Its general structure is inspired in the Route Generation Algorithm (RGA) of Baaj and Mahmassani, where its original expansion of routes by inserting individual vertices is replaced by a strategy of insertion of pairs of vertices. The algorithm proposed, called Pair Insertion Algorithm (PIA) can be used to generate initial solutions for a local improvement or evolutionary algorithm, as well as to complete an unfeasible solution with respect to demand covering constraints. Numerical results comparing PIA with RGA over a real test case show that both algorithms produce solutions with similar quality from the users viewpoint (in terms of in-vehicle travel time), while the former produces better solutions from the operators viewpoint (in terms of number of routes and total route duration) and requires a higher execution time. Since the TNDP arises in a context of strategic planning, a solution that reduces the operation cost of the system is highly desirable, even though it takes more time to be computed. The experimental study of the proposed algorithm also shows its ability to produce diverse solutions in both decision and objective spaces; this is a useful property when looking at the use of PIA as a subroutine in the context of another algorithm such as metaheuristics, in particular for a multi-objective problem like TNDP.     

考虑港口拥堵因素的沿海海运网络优化

沿海运输权制度是沿海运输是否保留给本国船舶或者向外国籍船舶开放的制度。港口拥堵主要发生在海运网络的枢纽港上。通过考虑沿海运输权和港口拥堵对轴辐式海运网络加以优化,以海运网络内货物运输总成本最小化为目标函数,构建一个小规模整数规划模型。从欧亚航线覆盖的主要地区中选取10个港口组成海运网络进行算例分析,并使用CPLEX软件进行求解,研究结果表明,通过考虑枢纽港间货物运输的规模经济效应和产生的拥堵成本,可合理地确定枢纽港的位置;若允许沿海捎带,外资航运企业将会改变货物中转的港口。     

无线网络中的跨层设计

随着网络的不断发展，跨层设计越来越多的受到了关注。本文首先介绍了传统网络层次的缺陷和跨层设计在下一代网络中的重要性，然后阐述了目前此项研究中已有的跨层设计方法，最后对各种方法的优缺点进行总结和比较并提出了跨层设计的难度和待解决的问题。     

Schedule design for sustainable container supply chain networks with port time windows

This paper studies a practical liner shipping schedule design problem with port time windows for container supply chain networks. A mixed-integer nonlinear non-convex model that incorporates the availability of ports is proposed to minimize the sum of ship cost and fuel cost (and thereby pollutant emission). In view of the structure of the problem, we reformulate it as an integer linear optimization model and propose an iterative optimization approach. The proposed solution method is applied to two liner networks operated by a global shipping line.     

A demand based route generation algorithm for public transit network design

This paper presents a public transit network route generation algorithm. The main contribution of this work is the introduction of new route generation algorithms. The proposed route generation algorithm is tested on Mandl׳s Swiss Road network and the four large networks presented in recent previous work. Three parameters are used to evaluate the route sets generated by the proposed algorithm. These are the zero transfer percentage, the average travel time, and the total route cost. The route sets generated for the large networks have better parameter values compared to recent previous work.     

考虑道路扩建的区域物流网络设计优化模型

通过对区域物流网络中边、点上费用、容量、流量等的分析,结合实际问题中对道路扩建和物流设施容量设计决策的需要,构建基于物流时间需求的区域物流网络设计数学模型。模型以最小化物流网络构建成本、初期运营成本和物流时间需求惩罚成本为目标,基于网络中物流量的特征给出了约束条件,分析模型的特点开发了改进的拉格朗日松弛算法并予以求解。计算机软件对模型和算法的仿真给出了物流网络构建中各项成本之间的关系,验证了模型和算法的有效性和实用性。     

On the impact of network latency on distributed systems design

Research in distributed database systems to date has assumed a “variable cost” model of network response time. However, network response time has two components: transmission time (variable with message size) and latency (fixed). This research improves on existing models by incorporating a “fixed plus variable cost” model of the network response time. In this research, we: (1) develop a distributed database design approach that incorporates a “fixed plus variable cost”, network response time function; (2) run a set of experiments to create designs using this model, and (3) evaluate the impact the new model had on the design in various types of networks. This revised version was published online in July 2006 with corrections to the Cover Date.     

An integrated optimization method for tactical-level planning in liner shipping with heterogeneous ship fleet and environmental considerations

The maritime transportation flows and container demand have been increasing over time, although the COVID-19 pandemic may slow down this trend for some time. One of the common strategies adopted by shipping lines to efficiently serve the existing customers is the deployment of large ships. The current practice in the liner shipping industry is to deploy a combination of ships of different types with different carrying capacities (i.e., heterogeneous fleet), especially at the routes with a significant demand. However, heterogeneous fleets of ships have been investigated by a very few studies addressing the tactical liner shipping decisions (i.e., determination of service frequency, ship fleet deployment, optimization of ship sailing speed, and design of ship schedules). Moreover, limited research efforts have been carried out to simultaneously capture all the major tactical liner shipping decisions using a single solution methodology. Therefore, this study proposes an integrated optimization model that addresses all the major tactical liner shipping decisions and allows the deployment of a heterogeneous ship fleet at each route, considering emissions generated throughout liner shipping operations. The model’s objective maximizes the total turnaround profit generated from liner shipping operations. A decomposition-based heuristic algorithm is presented in this study to solve the model proposed and efficiently tackle large-size problem instances. Numerical experiments, carried out for a number of real-world liner shipping routes, demonstrate the effectiveness of the proposed methodology. A set of managerial insights, obtained from the proposed methodology, are also provided.     

Optimal fleet design in a ship routing problem

The problem of deciding an optimal fleet (the type of ships and the number of each type) in a real liner shipping problem is considered. The liner shipping problem is a multi-trip vehicle routing problem, and consists of deciding weekly routes for the selected ships. A solution method consisting of three phases is presented. In phase 1, all feasible single routes are generated for the largest ship available. Some of these routes will use only a small portion of the ship's capacity and can be performed by smaller ships at less cost. This fact is used when calculating the cost of each route. In phase 2, the single routes generated in phase 1 are combined into multiple routes. By solving a set partitioning problem (phase 3), where the columns are the routes generated in phases 1 and 2, we find both the optimal fleet and the coherent routes for the fleet.     

The generalized fixed-charge network design problem

In this paper we present the generalized fixed-charge network design (GFCND) problem. The GFCND problem is an instance of the so-called generalized network design problems. In such problems, clusters instead of nodes have to be interconnected by a network. The network interconnecting the clusters is a fixed-charge network, and thus the GFCND problem generalizes the fixed-charge network design problem. The GFCND problem is related to the more general problem of designing hierarchical telecommunication networks.     

Slot co-chartering and capacity deployment optimization of liner alliances in containerized maritime logistics industry

With the growing traffic of containerized shipping worldwide, container liners have seen increasing cooperation. Slot co-chartering has drawn wide attention as a way of cooperation within liner alliances. However, liners face the issue of finding proper measures to optimize alliance operations. In response to this, this paper comprehensively considers shipping capacity dispatch for containerized shipping companies within liner alliances. First, we explained the general rules of liner shipping dispatch and analyzed the interfering factors. Second, we created a liner shipping capacity dispatch model without consideration of slot co-chartering costs and a liner shipping capacity dispatch model with consideration of slot co-chartering costs and proposed a new column generation algorithm to solve both problems. Third, we tested our algorithm in a real case of a large Chinese containerized shipping company, which belongs to Ocean Alliance, and an optimal ship dispatch strategy on relevant routes and a decision on optimal slot chartering can be reached. Computational results indicate that the proposed column generation algorithm exhibits effective and efficient performance for large-scale slot co-chartering in liner shipping.     

非轴辐式快递网络的航线规划研究

快递服务要求在一个时间限制内（24小时、48小时等）将货物从起点运送到目的地,由于对时间的严格要求,长距离的运输一般由飞机完成。回顾了快递航线网络规划的经典模型,并研究了多货物流的非轴辐式快递网络,建立数学模型,分别提出了基于NLP模型和改进的ESSND模型的两种求解方法。最后,设计算例,详细说明了这两类方法的使用,并得出结论改进的ESSND模型能够获得接近最优的结果。     

Transit network timetabling and vehicle assignment for regulating authorities

In the literature on transit planning, network timetabling and vehicle scheduling are usually treated as separate problems. In this paper, we focus on combining important features of these two steps and propose a simultaneous solution approach to redefine timetables with the objective of bringing improvements to both quality of service and vehicle costs incurred. This includes the objectives of quantity and quality of the transfers proposed, evenness of the line headways, fleet size and length of the deadheads. The model proposed for this simultaneous approach is adapted to the problem faced by regulating authorities, encouraging intermodality and taking into account a variety of practical features. We introduce an optimization procedure based on Iterated Local Search and present computational experiments carried out on data from a large existing transit network, showing substantial improvements in both quality of service and level of resources compared to the current practice.     

计算机网络信息存储安全设计

计算机所具有的连接方式因其多样性、应用技术复杂性和网络广泛性以及互相关联性等特征,导致计算机网络信息存储安全问题的出现并且愈发复杂。针对来自各方面的诸多威胁和系统本身的脆弱性,通过建立计算机网络信息的危险控制模型、控制网络信息访问数据、鉴别网络信息用户身份等方法,制定出计算机网络信息存储安全的具体措施,以此来保证存储信息系统的运行安全。