Repository of the University of Hasselt containing publications in the fields of statistics, computer science, information strategies and material from the Institute for behavioural sciences.
Techniques for modelling workflows and their support of reuse - JANSSENS, Gerrit; Verelst, J.; Weyn, B.
Several authors propose their own technique based on Petri Nets to model workflow processes. Most of them recognise the adaptability problem inherent to workflows, viz. the frequently and/or radically changing character due to changing business process rules, but suggest totally different solutions. Because the proposed techniques are fundamentally different, eleven of these techniques are briefly discussed and compared. Next, we survey approaches to reuse in the workflow field and we classify them in a framework derived from the information systems literature.
De invloed van de winkel en de consument op winkeltrouw - BLOEMER, Johanna; Odekerken-Schroder, G.J.
In deze studie staan de effecten van het imago van de winkel en de relatiegeneigdheid van de consument op winkeltrouw centraal. Hierbij wordt tevens aandacht besteed aan de rol van positieve gevoelens, tevredenheid, vertrouwen en commitment. De data zijn verkregen uit een steekproef van 357 consumenten van een grote Belgische supermarktketen. LISREL-resultaten bevestigen de veronderstelde relaties tussen de constructen aangezien tien van de elf hypothesen kunnen worden ondersteund. Het onderzoek toont aan dat het imago van de winkel en de relatiegeneigdheid van de consument beide een duidelijk positief effect hebben op winkeltrouw via positieve gevoelens, tevredenheid, vertrouwen en commitment. Een...
Travel Time Evaluation of a U-Turn Facility Comparison with a Conventional Signalized Intersection - PIRDAVANI, Ali; BRIJS, Tom; BELLEMANS, Tom; WETS, Geert
Drivers on high-volume arterials with signalized intersections often face congestion during peak hours. This congestion, primarily through movement, decreases the traffic performance of the intersection. The primary delay at conventional intersections is caused by interactions between high left-turn movements and the opposing through maneuvers. Unconventional intersection designs have been proposed to decrease intersection delay and travel time, for example, by redirecting left turns from the minor approach away from the main intersection and replacing them with a right turn followed by U-turn. The U-turn intersection investigated in this study is geometrically designed with a raised island, which provides a protected...
Simulation and optimisation of intermodal barge transport networks - CARIS, An
This is a summary of the author's PhD thesis supervised by Gerrit Janssens and Cathy Macharis and defended on 7 May 2010 at the Hasselt University, Belgium. The thesis is written in English and is available from the author upon request. This work deals with two key aspects in the competitiveness of intermodal transport making use of inland navigation. The first part of the thesis studies bundling of freight in intermodal barge transport networks. Alternative bundling strategies for container barge transport are compared by means of discrete event simulation. Cooperation between inland barge terminals to bundle freight flows is modelled...
A Bayesian model for ranking hazardous sites - BRIJS, Tom; Karlis, Dimitris; VAN DEN BOSSCHE, Filip; WETS, Geert
This paper proposes a methodology to rank dangerous road locations. The model is innovative in two respects. Firstly, it makes use of relevant information per accident location, including the total number of accidents, the number of fatalities, as well as the number of light and severe injuries. Secondly, the model includes a cost function to rank the sites with respect to their total expected cost to the society. Bayesian estimation for the model via a MCMC approach is proposed.
Variations in road accident counts: an explanatory time-series model - VAN DEN BOSSCHE, Filip; BRIJS, Tom; WETS, Geert
Monthly traffic accident counts show a yearly recurring pattern. The number of accidents for some months always seems to be higher or lower than average. We investigate a range of factors that can explain this variation in monthly accident counts. Apart from legal, economic and climatologic factors, monthly accident statistics are subject to calendar effects and seasonal variation. The number of accidents may vary with the number of days per month or with the number of times each day of the week occurs. Accident counts are also affected by seasonal variation. Factors like weather and holidays vary strongly with the...
The interaction between forecasting methods and inventory management policies for intermittent demand - RAMAEKERS, Katrien
Inventory systems have to cope with uncertainty in demand. The inventory control literature mostly makes use of the Normal or Gamma distributions for describing the demand in the leadtime. The Poisson distribution has been found to provide a reasonable fit when demand is very low (only a few pieces per year). Less attention has been paid to irregular demand. This type ofdemand is characterised by a high level of variability, but may be also of the intermittent type, i.e. demand peaks follow several periods of zero or low demands.
In such a situation forecasting demand is considered difficult. This research investigates...
Evaluation of solution generating methods for various types of pickup and delivery problems - CARIS, An; JANSSENS, Gerrit
The Pickup and Delivery Problem (PDP) is an extension to the classical Vehicle RoutingProblem (VRP) where customers may both receive and send goods. A fleet of vehicles is required to pickup and deliver goods at customer locations. A wide variety of commercial service companies can be modelled as a PDP.
PDP appears in literature in various forms: delivery-first, pickup-second PDP, mixed pickups and deliveries and simultaneous pickups and deliveries. In the first model a vehicle can pick up goods only after its complete load has been delivered. The second model allows pickups anddeliveries in any sequence on a vehicle route. In...
Regular events in travel behaviour research: setup of a longitudinal websurvey - COOLS, Mario; MOONS, Elke; WETS, Geert
One of the leading paradigms in modern travel behaviour research is the activity based approach, which considers travel as a derivative from the activities that individuals and households need or wish to perform. Longitudinal designs provide the required framework for a better understanding of the dynamics of travel behaviour. Longitudinal data can be used to analyze behavioural adjustments some time before (response leads) or after (response lags) the occurrence of an event, or for instance to analyze routine behaviour.
The questionnaire used to collect the data will be an activity diary. The respondents are asked to fill in all their activities...
On the use of bounds on stop-loss premium for an inventory management decision problem - RAMAEKERS, Katrien; JANSSENS, Gerrit
A specific integral, which is used in insurance mathematics for the determination of a stop-loss premium, corresponds to the definition of a performance characteristic of an inventory management decision problem. It is investigated whether the operational management problem might benefit from specific results obtained in the actuarial world. In the case little information is available on the demand distribution during the lead-time, which is relevant in inventory decision-making, interesting results might be used from the actuarial problem where limited information (e.g., only a few moments of the claim size distribution) is known. With a limited transformation of the actuarial results,...
Investigating Effect of Holidays on Daily Traffic Counts: Time Series Approach - COOLS, Mario; MOONS, Elke; WETS, Geert
Different modeling philosophies are explored to explain and to forecast daily traffic counts. The main objectives of this study are the analysis of the impact of holidays on daily traffic and the forecasting of future traffic counts. Data from single inductive-loop detectors, collected in 2003, 2004, and 2005, were used for the analysis. The different models investigated showed that the variation in daily traffic counts could be explained by weekly cycles. The Box–Tiao modeling approach was applied to quantify the effect of holidays on daily traffic. The results showed that traffic counts were significantly lower for holiday periods. When the...
Sensitivity Analysis of a Genetic Algorithm for a Competitive Facility Location Problem - Pangilinan, Jose Maria A.; JANSSENS, Gerrit; CARIS, An
The paper describes an application of a multi-objective evolutionary algorithm that finds Pareto-optimal solutions to a competitive facility location problem and reports a sensitivity analysis of the evolutionary algorithm model. A genetic algorithm which uses non-uniform mutation and continuous recombination is developed to find solutions to the bi-objective location problem. Results show that the genetic algorithm can find solutions close to the Pareto-optimal set in polynomial time and results from sensitivity analysis show that the mutation rate has the largest influence on the output among the input factors.
An integrated activity-based modelling framework to assess vehicle emissions: approach and application - BECKX, Carolien; INT PANIS, Luc; Vankerkom, Jean; JANSSENS, Davy; WETS, Geert; Arentze, Theo
Owing to the richer set of concepts which are involved in activity-based transportation models, the potential advantages of an activity-based approach for air quality purposes have been recognized for a long time. However, models that have been developed along these lines are still scarce. In this research the activity-based model ALBATROSS was used in combination with the emission model MIMOSA to assess the travelled distances and the mobile source emissions produced by passenger cars in the Netherlands. The fact that this approach is based on hourly travel and emission values, rather than on aggregated results or peak hour values, a...
An Agent-Based System for Simulating Dynamic Choice-Sets - Han, Q.; Arentze, T.; TIMMERMANS, Harry; JANSSENS, Davy; WETS, Geert
Contributing to the recent interest in the dynamics of activity-travel patterns, this paper discusses a framework for the dynamic formation of location choice-sets. It is based on the concepts of aspiration, activation and expected utility. Based on principles of Bayesian learning, reinforcement learning and social comparison theories, the framework specifies functions for experience-based learning, extended and integrated with social learning.
Application of Online Regression Tree Induction to Forecast Traffic Flows - VANHULSEL, Marlies; JANSSENS, Davy; VANHOOF, Koen; WETS, Geert
Modelling efforts aiming at predicting traffic flows accurately should be capable of handling a continuous stream of data while being able to account for structural changes. To this end, the current research proposes three regression tree induction algorithms, including a batch, incremental and hybrid batch/incremental technique. These algorithms are discussed, implemented and evaluated based on their predictive power and coputational requirements. The incremental and batch/incremental algorithms prove to be particularly suited as on-line learning approaches, whereas the batch algorithm needs to be adapted in order to handle a continuous stream of data. The outcomes of the batch/incremental and batch algorithms...
Improving associative classification by incorporating novel interestingness measures - Lan, Y; JANSSENS, Davy; Chen, GQ; WETS, Geert
Associative classification has aroused significant attention in recent years and proved to be intuitive and effective in many cases. This paper aims at achieving more effective associative classifiers by incorporating two novel interesting measures, i.e. intensity of implication and dilated chi-square. The former is proposed in the beginning for mining meaningful association rules and the latter is designed by us to reveal the interdependence between condition and class variables. Each of these two measures is applied, instead of confidence, as the primary sorting criterion under the framework of the well-known CBA algorithm in order to organize the rule sets in...
Evaluating the performance of cost-based discretization versus entropy- and error-based discretization - JANSSENS, Davy; WETS, Geert; BRIJS, Tom; VANHOOF, Koen
Discretization is defined as the process that divides continuous numeric values into intervals of discrete categorical values. In this article, the concept of cost-based discretization as a pre-processing step to the induction of a classifier is introduced in order to obtain an optimal multi-interval splitting for each numeric attribute. A transparent description of the method and the steps involved in cost-based discretization are given. The aim of this paper is to present this method and to assess the potential benefits of such an approach. Furthermore, its performance against two other well-knwon methods, i.e. entropy- and pure error-based discretization is examined....