Airline planning benchmark problems—Part II: Passenger groups,utility and demand allocation

This paper is the second of two papers entitled “Airline Planning Benchmark Problems”, aimed at developing benchmark data that can be used to stimulate innovation in airline planning, in particular, in flight schedule design and fleet assignment. The former has, to date, been under-represented in the optimisation literature, due in part to the difficulty of obtaining data that adequately reflects passenger choice, and hence schedule revenue. Revenue models in airline planning optimisation only roughly approximate the passenger decision process. However, there is a growing body of literature giving empirical insights into airline passenger choice. Here we propose a new paradigm for passenger modelling, that enriches our representation of passenger revenue, in a form designed to be useful for optimisation. We divide the market demand into market segments, or passenger groups, according to characteristics that differentiate behaviour in terms of airline product selection. Each passenger group has an origin, destination, size (number of passengers), departure time window, and departure time utility curve, indicating willingness to pay for departure in time sub-windows. Taking as input market demand for each origin–destination pair, we describe a process by which we construct realistic passenger group data, based on the analysis of empirical airline data collected by our industry partner. We give the results of that analysis, and describe 33 benchmark instances produced.     

Box-Jenkins identification revisited—Part III : Multivariable systems

Part I of this series of three papers handles the identification of single input single output Box-Jenkins models on arbitrary frequency grids in an open and closed loop setting. Part II discusses the computational aspects and illustrates the theory on simulations and a real life problem. This paper extends the results of Parts I and II to multiple input multiple output systems. Contrary to the classical time domain approach, the presented technique does not require symbolic calculus for multiple output polynomial Box-Jenkins models.     

Dirac,dynamic information retrieval of atomic codes : 1. Physical design criteria

This communication describes a computer code, acronym DIRAC, to assist atomic physicists to control and process a library of computer codes. The objectives of DIRAC are to facilitate the preparation of input, the storage of output within the computer's memory hierarchy, and the comparative analysis of results of the codes from the library. At the present time, the library consists of codes for calculating electron and photon processes in atomic systems with L-S coupling. Library members can used to identify and store experimental results. The DIRAC system is based on the availability of an interactive graphics device and has been implemented on IBM-2250's attached to either the IBM System 360/65 of 360/91.     

Breaking the search space symmetry in partitioning problems: An application to the graph coloring problem

Many problems consist in splitting a set of objects into different groups so that each group verifies some properties. In practice, a partitioning is often encoded by an array mapping each object to its group numbering. In fact, the group number of an object does not really matter, and one can simply rename each group to obtain a new encoding. That is what we call the symmetry of the search space in a partitioning problem. This property may be prejudicial for optimization methods such as evolutionary algorithms (EA) which require some diversity during the search.     

How can the Web help build customer relationships?: An empirical study on e-tailing

The Web is increasingly being viewed as a tool and place to enhance customer relationship. In this paper we defined a model to analyze the Web characteristics that aid in building customer relationships and then used this model to examine consumer relationship building mechanisms in online retailing (e-tailing). Through a survey of 177 shoppers who had bought books, CDs, or DVDs online, the causal model was validated using LISREL; 13 out of 14 hypotheses were supported. This research has contributed to both theory and practice by providing a validated model to analyze online consumer relationship building and suggesting mechanisms to help e-tailers focus on online consumer relationship management.     

Agent virtual machine for automation controllers: Example application: Shipboard automation

We are interested in providing an agent infrastructure for truly distributed control. Requirements include multiple language implementations, so that this agent host environment can exist in both real-time controllers and contain the ability to operate with external agent systems. Our first infrastructure, the Autonomous Cooperative System (ACS), accomplished these goals, but presented other issues. Although ACS has been successfully deployed on commercial controllers, new releases of controllers will cause complications in the evolution of the software and adoption of future functionality. We need to establish a formal integration procedure of the agent functionality with the controllers and to transform the underlying system into a fully integrated and open heterogeneous system. We use a shipboard automation example to demonstrate the use of the agent virtual machine. With this system, the shipboard automation system is designed as a distributed and survivable environment, thereby spreading intelligence throughout the controllers and not in central locations.