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Document Server@UHasselt (39,005 recursos)
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.

Quantitative Methods - Logistics

Mostrando recursos 1 - 20 de 78

1. Multiple Criteria Performance Analysis of Non-dominated Sets Obtained by Multi-objective Evolutionary Algorithms for Optimisation - Janssens, Gerrit K.; Pangilinan, Jose Maria
The paper shows the importance of a multi-criteria performance analysis in evaluating the quality of non-dominated sets. The sets are generated by the use of evolutionary algorithms, more specifically through SPEA2 or NSGA-II. Problem examples from different problem domains are analyzed on four criteria of quality. These four criteria namely cardinality of the non-dominated set, spread of the solutions, hyper-volume, and set coverage do not favour any algorithm along the problem examples. In the Multiple Shortest Path Problem (MSPP) examples, the spread of solutions is the decisive factor for the 2SI1M configuration, and the carchnality and set coverage for the...

2. Pickup and delivery selection problem - Maes, T.; Caris, A.; Ramaekers, K.; Janssens, G.K.; Bellemans, T.
This paper focuses on the modelling of carrier decisions within an activity-based freight transportation model. To model freight transport, the different actors who are included in the decision making process have to be represented. One of these actors is the carrier. This paper formulates the decisions of the carrier as a selective pickup and delivery problem. To be able to better represent the influence of carrier decisions on the logistic module within an activity based freight transportation model. The objective is to maximize the profit gained, by selecting transport requests. A local search heuristic is presented to solve the problem.

3. Corridor network design in hinterland transportation systems - Caris, An; Macharis, Cathy; Janssens, Gerrit K.
In this paper the design of the service network in intermodal barge transport is studied. The network of inland barge terminals is modelled to demonstrate potential cooperations in a corridor network. Cooperation between inland terminals leads to bundling of freight flows in the hinterland of major ports. A service network design model for intermodal barge transport is developed and applied to the hinterland network of the port of Antwerp in Belgium. Selected cooperation schemes are simulated by means of a discrete event simulation model for intermodal barge transport and compared with simulation results of bundling in the port area. Cooperation...

4. Prediction of asthma exacerbations in children: results of a one-year prospective study - Robroeks, C. M. H. H. T.; van Vliet, D.; J??bsis, Q.; BRAEKERS, Roel; Rijkers, G. T.; Wodzig, W. K. W. H.; Bast, A.; Zimmermann, L. J. I.; Dompeling, E.
Background Underdiagnosis and low levels of asthma control are frequent occurring problems in patients with asthma. Objective The study aim was to evaluate the ability of non-invasive inflammatory markers in exhaled breath to predict exacerbations of childhood asthma, and to assess the time course of changes in these exhaled markers before, during and after exacerbations. Methods The design was a prospective one-year longitudinal study. Regular two-month visits at the outpatient clinic were performed. Forty children with asthma (aged 6-16 years) participated. The primary outcome measure was the occurrence of an exacerbation. Assessment was made of the presence and severity of...

5. An empirical evaluation of Martins' algorithm for the multi-objective shortest path problem - Janssens, Gerrit K.; Pangilinan, José Maria
The Shortest Path Problem is a popular optimization problem in operations research due to its wide range of practical applications. In most cases a single objective is considered, while also the multi-objective case has useful applications. The algorithms by Martins is considered very efficient. This study evaluates this algorithm by comparing it to a brute force algorithm as a first step to develop evolutionary algorithms for the multi-objective case. Experiments confirm the strength of the Martins’ algorithm.

6. The life-cycle of Electronic Data Interchange: emergence from the dust till a doubtful survival in the future - Janssens, Gerrit K.
The introduction of internet applications in e-commerce made many adopters think that EDI would soon disappear. But the trend in logistics towards closer collaboration in supply chains made on the other hand the impact of EDI larger. A resultant of those forces will probably lead to a new type of EDI, which integrates with other technologies. Early studies on EDI were promoting its use because of savings in administrative work. But due to intra-corporation management model changes, today‟s savings should be looked for rather in lower inventory holding, fewer obsolete materials, and lower premium freight. The traditional potential of EDI...

7. Minimax optimization approach for the robust vehicle routing problem with time windows and uncertain travel times - Manisri, Tharinee; Mungwattana, Anan; Janssens, Gerrit K.
This paper focuses on the robust vehicle routing problem with time windows (RVRPTW). It involves servicing a set of customers, with earliest and latest time deadlines, and a constant service time when the vehicle arrives to the customers. The various demands are served by capacitated vehicles with limited travel time to return to the depot. The objective is to find a robust solution that has the best worse-case performance over a set of possible scenarios under a robustness criterion. This paper proposes a two-phase algorithm to solve a minimax optimization problem with uncertain travel times. The algorithm includes the Modified Push-Forward...

8. Electronic Data Interchange: from its Birth to its New Role in Logistics Information Systems - Janssens, Gerrit K.
The introduction of internet applications in e-commerce made many adopters think that EDI would soon disappear. But the trend in logistics towards closer collaboration in supply chains made on the other hand the impact of EDI larger. A resultant of those forces will probably lead to a new type of EDI, which integrates with other technologies. Early studies on EDI were promoting its use because of savings in administrative work. But due to intra-corporation management model changes, today’s savings should be looked for rather in lower inventory holding, fewer obsolete materials, and lower premium freight. The traditional potential of EDI...

9. Electronic data intercharge: from its birth to its new role in logistics information systems - JANSSENS, Gerrit
The introduction of internet applications in e-commerce made many adopters think that EDI would soon disappear. But the trend in logistics towards closer collaboration in supply chains made on the other hand the impact of EDI larger. A resultant of those forces will probably lead to a new type of EDI, which integrates with other technologies. Early studies on EDI were promoting its use because of savings in administrative work. But due to intra-corporation management model changes, today???s savings should be looked for rather in lower inventory holding, fewer obsolete materials, and lower premium freight. The traditional potential of EDI...

10. An exact algorithm for the full-truckload pick-up and delivery problem with time windows: concept and implementation details - Janssens, Gerrit; Braekers, Kris
Intermodal goods transport is characterized by a main transport by rail, barge or seaborne vessel, preceded and followed by short in time but expensive road transport. Many times trucks pick-up or deliver a single container which leads to a full truckload vehicle routing problem in terms of economically efficient transport services. Time windows induced by the customer or due to external situations increase the complexity of an efficient planning by a logistics provider. An exact algorithm for this type of pick-up and delivery problem is developed and the details of its implementation are explained. A set partitioning problem is automatically...

11. Simulation of logistic decisions within a freight transportation model - Maes, Tabitha; Ramaekers, Katrien; Caris, An; Janssens, Gerrit; Bellemans, Tom
This paper presents a conceptual framework of a freight transportation model. The focus of the framework lies on simulating the logistic decisions of rms. In this pa- per, a rst application is discussed on a small test sam- ple of ten zones. Inside is gained into the working of the model and into potential problems when implementing the framework on a country-size scale.

12. Simulation of logistic decisions within a freight transportation model - Maes, Tabitha; Ramaekers, Katrien; Caris, An; Janssens, Gerrit; Bellemans, Tom
This paper presents a conceptual framework of a freight transportation model. The focus of the framework lies on simulating the logistic decisions of firms. In this paper, a first application is discussed on a small test sample of ten zones. Inside is gained into the working of the model and into potential problems when implementing the framework on a country-size scale.

13. Modelling logistic decisions of firms and carriers - Maes, Tabitha; Ramaekers, Katrien; Caris, An; Janssens, Gerrit; Bellemans, Tom
Due to the rapid increase of freight transport, more attention is paid to the modelling of future freight flows. This paper focuses on the logistic decisions made within freight transportation models. Two main logistic decisions are highlighted. The first one is the choice of an appropriate inventory level and transport mode, made by the firm responsible for the transport. For this problem most authors refer to the inventory-theoretic approach. The second item is the order request selection process performed by the carrier to maximize his profit. This problem may be formulated in the form of a pickup and delivery selection...

14. A deterministic annealing algorithm for a bi-objective full truckload vehicle routing problem in drayage operations - Braekers, Kris; Caris, An; Janssens, Gerrit
Drayage operations involve transporting loaded and empty containers in the hinterland of a port. In this paper a full truckload vehicle routing problem in drayage operations is studied. Either the origin or destination of empty container transport requests is unknown in advance. A two-phase solution algorithm using deterministic annealing is presented to solve the bi-objective problem, minimizing the number of vehicles used and minimizing total distance travelled. Results on random problem instances show that the algorithm is able to find sets of non-dominated solutions of good quality in a small amount of computation time.

15. A decision support framework for intermodal transport policy - Macharis, C.; Caris, An; Jourquin, Bart; Pekin, E.
Purpose In recent years intermodal transport has received an increased attention due to problems of road congestion, environmental concerns and traffic safety. A growing recognition of the external effects of transport urges to go towards more sustainable transport modes. As a consequence, research and policy interest in intermodal freight transportation problems is growing. Methods In this paper the strengths of Operations Research (OR) modelling techniques applicable to decisions related to intermodal transport are used to develop a particular framework that is able to assess the performance of current and potential policy measures which affects the intermodal transport industry. The assessment...

16. Reducing transport costs and improving sustainability simultaneously through horizontal logistics collaboration: a case study - Van Lier, Tom; Macharis, Cathy; Caris, An; Vrenken, Huub
In this paper the potential of a more systematic bundling of the outbound freight flows out of three neighboring distribution centers (DCs) of the same company, each specialized in a specific product category and each using a separate planning system, is investigated. Most of the outbound flows are currently still transported by truck, so one way to simultaneously achieve lower transport costs and more sustainable logistics is through supply chain collaboration in outbound logistics. This paper investigates two possible options: horizontal internal collaboration across warehousing functions and horizontal external collaboration with a non-competitor. The first option looks at internal co-loading...

17. Challenges in Managing Empty Container Movements at Multiple Planning Levels - Braekers, Kris; Janssens, Gerrit; Caris, An
Empty container management deals with repositioning empty containers at minimum costs while fulfilling empty container demands. Due to imbalances in trade, some areas have a surplus of empty containers, while others have a shortage. Therefore, empty containers need to be repositioned globally to make sure that sufficient empty containers are available everywhere. Besides, empty containers need to be repositioned regionally between shippers, consignees, inland depots, terminals and ports in order to fulfil demand. In this paper, the focus is on the empty container management problem at a regional level. The problem is described in detail and opportunities for reducing empty...

18. Pareto-optimality of oblique decision trees from evolutionary algorithms - Maria Pangilinan, Jose; JANSSENS, Gerrit
This paper investigates the performance of evolutionary algorithms in the optimization aspects of oblique decision tree construction and describes their performance with respect to classification accuracy, tree size, and Pareto-optimality of their solution sets. The performance of the evolutionary algorithms is analyzed and compared to the performance of exhaustive (traditional) decision tree classifiers on several benchmark datasets. The results show that the classification accuracy and tree sizes generated by the evolutionary algorithms are comparable with the results generated by traditional methods in all the sample datasets and in the large datasets, the multiobjective evolutionary algorithms generate better Pareto-optimal sets than...

19. Holding costs under push or pull conditions - The impact of the Anchor Point - Beullens, Patrick; JANSSENS, Gerrit
Holding costs are traditionally determined from the investment in physical stock during a cycle. An alternative approach instead derives holding costs from Net Present Value (NPV) functions. It is known that applying both frameworks to the same system can lead to different holding cost valuations, but little explanation has been offered. By introducing the Anchor Point in a model, this paper shows, for four different systems, that traditional holding cost models (implicitly) assume pull conditions, while current NPV approaches model push conditions. This explains in part the differences between the methods. It is shown that the Anchor Point concept allows...

20. 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...

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