分布式系统中信息内容安全的通用模型研究

提出了分布式环境下确保应用程序中不同形式的信息内容安全的通用模型,并以Word应用程序为例实现该模型,论证了该模型的可行性。     

基于中间件的企业计算模型*

在分析中间件技术的基础上,提出在J2EE平台上引入SOA架构实现企业计算的模型,并围绕健壮、高效、复用和扩展等性能,重点阐述模型的设计模式、容器实例化组件的思想及组件间的通信技术.     

RFID系统在自动化码头的应用

现代信息技术的高速发展,带动了港口生产技术和管理技术的长足进步,在现行集装箱信息管理标准条件下,RFID系统结合现代计算机技术、现代电子技术、软件工程技术、数据库技术的最新成果实现了堆场进场道口的数据自动采集、设备自动控制、业务自动处理的高效的堆场系统。结合天津港堆场的自动化改造项目,对RFID系统的原理进行分析与探讨。     

A tabu search heuristic for the quay crane scheduling problem

This paper proposes a tabu search heuristic for the Quay Crane Scheduling Problem (QCSP), the problem of scheduling a fixed number of quay cranes in order to load and unload containers into and from a ship. The optimality criterion considered is the minimum completion time. Precedence and non-simultaneity constraints between tasks are taken into account. The former originate from the different kind of operations that each crane has to perform; the latter are needed in order to avoid interferences between the cranes. The QCSP is decomposed into a routing problem and a scheduling problem. The routing problem is solved by a tabu search heuristic, while a local search technique is used to generate the solution of the scheduling problem. This is done by minimizing the longest path length in a disjunctive graph. The effectiveness of our algorithm is assessed by comparing it to a branch-and-cut algorithm and to a Greedy Randomized Adaptive Search Procedure (GRASP).     

Institutional pressures and mindful IT management: The case of a container terminal in China

Although it has been only ten years in operations, Yantian International Container Terminals Limited (YICT) has evolved as a world-class container terminal and become the first Chinese port to receive the Best Global Container Port of the Year award for 2005–2006, as well as being designated China's best container terminal in terms of operational efficiency for 2008. A success factor of YICT is its extensive use of IT in managing and enhancing the productivity and services of the port operations. Premised upon Institutional Theory and the organizational mindfulness perspectives (preoccupation with failure and success, reluctance to simplify interpretations, sensitivity to operations, commitment to resilience, and reliance on expertise over formal authority) and using case study methodology, we examined the institutional pressures faced by YICT in its IT management (ITM), and determined how YICT coped with its institutional pressures during its IT development.     

Immunity-based hybrid evolutionary algorithm for multi-objective optimization in global container repositioning

The development of evolutionary algorithms for optimization has always been a stimulating and growing research area with an increasing demand in using them to solve complex industrial optimization problems. A novel immunity-based hybrid evolutionary algorithm known as Hybrid Artificial Immune Systems (HAIS) for solving both unconstrained and constrained multi-objective optimization problems is developed in this research. The algorithm adopts the clonal selection and immune suppression theories, with a sorting scheme featuring uniform crossover, multi-point mutation, non-dominance and crowding distance sorting to attain the Pareto optimal front in an efficient manner. The proposed algorithm was verified with nine benchmarking functions on its global optimal search ability as well as compared with four optimization algorithms to assess its diversity and spread. Sensitivity analysis was also carried out to investigate the selection of key parameters of the algorithm. It is found that the developed immunity-based hybrid evolutionary algorithm provides a useful means for solving optimization problems and has successfully applied to the problem of global repositioning of containers, which is one of a constrained multi-objective optimization problem. The developed HAIS will assist shipping liners on timely decision making and planning of container repositioning operations in global container transportation business in an optimized and cost effective manner.     

A fast heuristic for quay crane scheduling with interference constraints

This paper considers the problem of scheduling quay cranes which are used at sea port container terminals to load and unload containers. This problem is studied intensively in a recent stream of research but still lacks a correct treatment of crane interference constraints. We present a revised optimization model for the scheduling of quay cranes and propose a heuristic solution procedure. At its core a Branch-and-Bound algorithm is applied for searching a subset of above average quality schedules. The heuristic takes advantage from efficient criteria for branching and bounding the search with respect to the impact of crane interference. Although the used techniques are quite standard, the new heuristic produces much better solutions in considerably shorter run times than all algorithms known from the literature.     

Agent based simulation architecture for evaluating operational policies in transshipping containers

An agent based simulator for evaluating operational policies in the transshipment of containers in a container terminal is described. The simulation tool, called SimPort, is a decentralized approach to simulating managers and entities in a container terminal. Real data from two container terminals are used as input for evaluating eight transshipment policies. The policies concern the sequencing of ships, berth allocation, and stacking rule. They are evaluated with respect to a number of aspects, such as, turn-around time for ships and traveled distance of straddle carriers. The simulation results indicate that a good choice in yard stacking and berthing position policies can lead to faster ship turn-around times. For instance, in the terminal studied the Overall-Time-Shortening policy offers fast turn-around times when combined with a Shortest-Job-First sequencing of arriving ships.     

An optimization model for the container pre-marshalling problem

In most container yards around the world, containers are stacked high to utilize yard space more efficiently. In these yards, one major factor that affects their operational efficiency is the need to re-shuffle containers when accessing a container that is buried beneath other containers. One way to achieve higher loading efficiency is to pre-marshal the containers in such a way that it fits the loading sequence. In this research, we present a mathematical model for the container pre-marshalling problem. With respect to a given yard layout and a given sequence that containers are loaded onto a ship, the model yields a plan to re-position the export containers within the yard, so that no extra re-handles will be needed during the loading operation. The optimization goal is to minimize the number of container movements during pre-marshalling. The resulting model is an integer programming model composed of a multi-commodity flow problem and a set of side constraints. Several possible variations of the model as well as a solution heuristic are also discussed. Computation results are provided.     

基于PLC的港口集装箱码头装卸模型下位机控制系统设计

根据港口集装箱码头装卸作业的实际情况,基于PLC,设计装卸模型所对应的下位机控制系统,并介绍设计过程中的技术要点、注意事项.