Robert Stahlbock

Container terminal operation and operations research — a classification and literature review

In the last four decades the container as an essential part of a unit-load-concept has achieved undoubted importance in international sea freight transportation. With ever increasing containerization the number of seaport container terminals and competition among them have become quite remarkable. Operations are nowadays unthinkable without effective and efficient use of information technology as well as appropriate optimization (operations research) methods. In this paper we describe and classify the main logistics processes and operations in container terminals and present a survey of methods for their optimization.

Operations research at container terminals: a literature update

The current decade sees a considerable growth in worldwide container transportation and with it an indispensable need for optimization. Also the interest in and availability of academic literatures as well as case reports are almost exploding. With this paper an earlier survey which proved to be of utmost importance for the community is updated and extended to provide the current state of the art in container terminal operations and operations research.

The impact of preprocessing on data mining: an evaluation of classifier sensitivity in direct marketing

Abstract Corporate data mining faces the challenge of systematic knowledge discovery in large data streams to support managerial decision making. While research in operations research, direct marketing and machine learning focuses on the analysis and design of data mining algorithms, the interaction of data mining with the preceding phase of data preprocessing has not been investigated in detail. This paper investigates the influence of different preprocessing techniques of attribute scaling, sampling, coding of categorical as well as coding of continuous attributes on the classifier performance of decision trees, neural networks and support vector machines. The impact of different preprocessing choices is assessed on a real world dataset from direct marketing using a multifactorial analysis of variance on various performance metrics and method parameterisations. Our case-based analysis provides empirical evidence that data preprocessing has a significant impact on predictive accuracy, with certain schemes proving inferior to competitive approaches. In addition, it is found that (1) selected methods prove almost as sensitive to different data representations as to method parameterisations, indicating the potential for increased performance through effective preprocessing; (2) the impact of preprocessing schemes varies by method, indicating different ‘best practice’ setups to facilitate superior results of a particular method; (3) algorithmic sensitivity towards preprocessing is consequently an important criterion in method evaluation and selection which needs to be considered together with traditional metrics of predictive power and computational efficiency in predictive data mining.

Genetic Algorithms for Support Vector Machine Model Selection

The support vector machine is a powerful classifier that has been successfully applied to a broad range of pattern recognition problems in various domains, e.g. corporate decision making, text and image recognition or medical diagnosis. Support vector machines belong to the group of semiparametric classifiers. The selection of appropriate parameters, formally known as model selection, is crucial to obtain accurate classification results for a given task. Striving to automate model selection for support vector machines we apply a meta-strategy utilizing genetic algorithms to learn combined kernels in a data-driven manner and to determine all free kernel parameters. The model selection criterion is incorporated into a fitness function guiding the evolutionary process of classifier construction. We consider two types of criteria consisting of empirical estimators or theoretical bounds for the generalization error. We evaluate their effectiveness in an empirical study on four well known benchmark data sets to find that both are applicable fitness measures for constructing accurate classifiers and conducting model selection. However, model selection focuses on finding one best classifier while genetic algorithms are based on the idea of re-combining and mutating a large number of good candidate classifiers to realize further improvements. It is shown that the empirical estimator is the superior fitness criterion in this sense, leading to a greater number of promising models on average.

A mathematical model of inter-terminal transportation

We present a novel integer programming model for analyzing inter-terminal transportation (ITT) in new and expanding sea ports. ITT is the movement of containers between terminals (sea, rail or otherwise) within a port. ITT represents a significant source of delay for containers being transshipped, which costs ports money and affects a port’s reputation. Our model assists ports in analyzing the impact of new infrastructure, the placement of terminals, and ITT vehicle investments. We provide analysis of ITT at two ports, the port of Hamburg, Germany and the Maasvlakte 1 & 2 area of the port of Rotterdam, The Netherlands, in which we solve a vehicle flow combined with a multi-commodity container flow on a congestion based time–space graph to optimality. We introduce a two-step solution procedure that computes a relaxation of the overall ITT problem in order to find solutions faster. Our graph contains special structures to model the long term loading and unloading of vehicles, and our model is general enough to model a number of important real-world aspects of ITT, such as traffic congestion, penalized late container delivery, multiple ITT transportation modes, and port infrastructure modifications. We show that our model can scale to real-world sizes and provide ports with important information for their long term decision making.

Efficiency considerations for sequencing and scheduling of double-rail-mounted gantry cranes at maritime container terminals

The current decade has seen a considerable growth in worldwide container transportation and with it, an indispensable need for optimisation. This paper seeks to investigate to which extent double-rail-mounted gantry cranes can help to improve a container terminals efficiency. A simulation study is conducted for evaluating different online algorithms for sequencing and scheduling of jobs for automated double-rail-mounted gantry cranes serving a terminals storage block. The experiments are based upon scenarios that are derived from the real world (Container Terminal Altenwerder, CTA, Hamburg, Germany) in order to investigate advantages as well as problems and limits of our algorithms and the specific crane systems. Furthermore, the influence of the horizontal transport at the blocks interfaces is examined.

Utility based data mining for time series analysis: cost-sensitive learning for neural network predictors

In corporate data mining applications, cost-sensitive learning is firmly established for predictive classification algorithms. Conversely, data mining methods for regression and time series analysis generally disregard economic utility and apply simple accuracy measures. Methods from statistics and computational intelligence alike minimise a symmetric statistical error, such as the sum of squared errors, to model ordinary least squares predictors. However, applications in business elucidate that real forecasting problems contain non-symmetric errors. The costs arising from over- versus underprediction are dissimilar for errors of identical magnitude, requiring an ex-post correction of the prediction to derive valid decisions. To reflect this, an asymmetric cost function is developed and employed as the objective function for neural network training, deriving superior forecasts and a cost efficient decision. Experimental results for a business scenario of inventory-levels are computed using a multilayer perceptron trained with different objective functions, evaluating the performance in competition to statistical forecasting methods.

Vehicle Routing Problems and Container Terminal Operations - An Update of Research

Containers came into the market for international conveyance of sea freight almost five decades ago. The breakthrough was achieved with large investments in specially designed ships, adapted seaport terminals with suitable equipment, and availability of containers. Today over 60 % of the world’s deep-sea general cargo is transported in containers and some routes are even containerized up to 100 %. Seaport container terminals face a high demand for advanced optimization methods. A crucial competitive advantage is the rapid turnover of the containers, which corresponds to an efficient handling of containers as well as to a decrease of the costs of the transshipment processes. One of the key concerns in this respect refers to various types of equipment at container terminals devoted to the routing of containers to achieve high productivity. For instance, a variety of vehicles is used for the horizontal transport at the quayside and at the landside.

Genetically Constructed Kernels for Support Vector Machines

Data mining for customer relationship management involves the task of binary classification, e.g. to distinguish between customers who are likely to respond to direct mail and those who are not. The support vector machine (SVM) is a powerful learning technique for this kind of problem. To obtain good classification results the selection of an appropriate kernel function is crucial for SVM. Recently, the evolutionary construction of kernels by means of meta-heuristics has been proposed to automate model selection. In this paper we consider genetic algorithms (GA) to generate SVM kernels in a data driven manner and investigate the potential of such hybrid algorithms with regard to classification accuracy, generalisation ability of the resulting classifier and computational efficiency. We contribute to the literature by: (1) extending current approaches for evolutionary constructed kernels; (2) investigating their adequacy in a real world business scenario; (3) considering runtime issues together with measures of classification effectiveness in a mutual framework.

Empirical comparison and evaluation of classifier performance for data mining in customer relationship management

In competitive consumer markets, data mining for customer relationship management faces the challenge of systematic knowledge discovery in large data streams to achieve operational, tactical and strategic competitive advantages. Methods from computational intelligence, most prominently artificial neural networks and support vector machines, compete with established statistical methods in the domain of classification tasks. As both methods allow extensive degrees of freedom in the model building process, we analyse their comparative performance and sensitivity towards data pre-processing in a real-world scenario.