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A Data Mining Analysis Applied to a Straightening Process Database Caprace, Jean-David ; ; Bair, Frédéric et al in Ship Technology Research = Schiffstechnik (2007), 54(4), 177-183 Detailed reference viewed: 40 (4 ULg)A Data Mining Analysis Applied to a Straightening Process Database Caprace, Jean-David ; ; Bair, Frédéric et al in Ship Technology Research = Schiffstechnik (2007), 54(4), 177-183 The complexity of modern manufacturing processes in a highly competitive environment forces the manufacturers to invest massively in automation and monitoring systems. The large data flows from these new ... [more ▼] The complexity of modern manufacturing processes in a highly competitive environment forces the manufacturers to invest massively in automation and monitoring systems. The large data flows from these new installations are sources of valuable and hidden knowledge that is so far hardly used. Data mining methods through integrated data analysis tools give a solution to this situation, allowing easy retrieval of knowledge starting from a data base. This is also a unique opportunity to learn faster about the process and to detect hidden and complex relationships between parameters involved. Within this framework we have decided to apply this data analysis method to the straightening process in shipbuilding. We refer to Caprace et al. (2007) for additional illustrations. In shipbuilding, the assembly of elements by welding involves temperature gradients within the ma- terial. These cause deformations which sometimes have to be reduced to obtain an acceptable surface flatness. The straightening process to eliminate these distortions for esthetical or functional reasons is labour intensive. Estimating the straightening impact on the production workload is interesting in the context of production simulation, cost assessment of ship hull, structure optimization, design for production, etc. To reach these objectives, the idea was to elaborate, through a data mining approach, a formula linking the straightening cost to the sections scantlings (plate thickness, dimension and inter-distance of longitudinal stiffeners, dimension and inter-distance of transversal frames) and to other section characteristics. This paper describes each stage of the methodology: data description, analysis of data quality, data exploration and finally choice of discriminatory attributes and the generation of the data-driven models. [less ▲] Detailed reference viewed: 134 (33 ULg)Least Cost Optimization of Large Passenger Vessels ; Caprace, Jean-David ; Losseau, Nicolas et al in Ships & Offshore Structures (2007), 2 The LBR-5 software allows optimizing ship structures according to objectives of higher inertia, less weight and/or lower cost. This last criterion offers the choice between two approaches of calculation ... [more ▼] The LBR-5 software allows optimizing ship structures according to objectives of higher inertia, less weight and/or lower cost. This last criterion offers the choice between two approaches of calculation. The first approach is based on a simplified assessment of the cost in which the total cost is described by rather simple analytical functions which bring into play on the one hand the design variables and on the other hand empirical parameters. In the second approach, the calculation of the cost is based on data specific to the shipyard. The material cost is analyzed according to the first approach while the cost of the labor considers each relevant operation of the ship building with respect to the LBR-5 model. A survey of all the tasks was carried out at Aker Yards France, and a thorough study made it possible to develop assessment tools of the labor cost for each operation as functions of the design variables. Plate straightening operations are also considered in this analysis. This paper presents a cost-based optimization study carried out on a large passenger ship structure with more than 600 design variables, by the use of the detailed approach for the cost calculation. The structural model has been formulated on the basis of technical documentation prepared by Aker Yards France. The loads and strength criteria applied on the model are considered according to classification society rules (Bureau Veritas). Results and conclusions of the study are presented. [less ▲] Detailed reference viewed: 158 (15 ULg)A Data Mining Analysis Applied to a Straightening Process Database Caprace, Jean-David ; Losseau, Nicolas ; et al in Conference on Computer Applications and Information Technology in the Maritime Industries (COMPIT) (2007, April) The paper presents the results of a data mining analysis aiming to improve the cost knowledge of the labour intensive straightening process. The data mining approach yields a formula linking the ... [more ▼] The paper presents the results of a data mining analysis aiming to improve the cost knowledge of the labour intensive straightening process. The data mining approach yields a formula linking the straightening cost to the sections scantlings (plate thickness, dimension and inter-distance of longitudinal stiffeners, dimension and inter-distance of transversal frames) and to other section characteristics. [less ▲] Detailed reference viewed: 90 (27 ULg)Integration of a Bottom-Up Production Cost Model in LBR-5 Optimization Tool ; Pircalabu, Eugen ; Caprace, Jean-David et al in Conference on Computer Applications and Information Technology in the Maritime Industries (COMPIT) (2007, April) The LBR-5 software allows the optimization of ship structures following different objectives as the highest inertia, least weight and/or least cost. The interest of European shipyards to optimize the ship ... [more ▼] The LBR-5 software allows the optimization of ship structures following different objectives as the highest inertia, least weight and/or least cost. The interest of European shipyards to optimize the ship structure is basically related to the production cost and mainly to the labor cost. In order to increase the quality of cost estimation, a bottom-up module has been developed by University of Liege in partnership with AKERYARDS France. This module has been validated on different types of ships (LNG, Cruise Vessels, Fast Ferry) and integrated in the LBR-5 optimization process. The bottom-up cost module has two important goals. The first one is to estimate accurately the labor cost of a given ship structure taking into account the production breakdown, the block splitting sequence and all the individual operations required by the fabrication process. The second one is to compute properly the sensitivities of the design objective (construction cost) related to the design variables (scantlings). The paper also presents the results of a validation test on a large passenger vessel. The effect of the bottom-up cost module on the optimal scantling and on the cost gain is highlighted through a comparison with the results obtained using a basic cost module. [less ▲] Detailed reference viewed: 102 (15 ULg)Minimization of Production Cost by use of an Automatic Cost Assessment Method and Simulation Caprace, Jean-David ; Bair, Frédéric ; Losseau, Nicolas et al in The Euro-Asia Maritime Network (EAMARNET) (2007, January) This paper will present different ways to minimize cost in shipbuilding industry. Amongst them we have the production simulation methods, the cost assessment methods and the optimization methods. Nowadays ... [more ▼] This paper will present different ways to minimize cost in shipbuilding industry. Amongst them we have the production simulation methods, the cost assessment methods and the optimization methods. Nowadays, cost assessment is a key task of an integrated ship design. The various methods to estimate the production cost differ with the known information (input data). The less information is detailed, the earlier a method can be used in the design process. The more information is used, the better we can assess the differences between design alternatives. The methods presented here and the “design for production” concept promise to increase the productivity trough the following points: a more accurate cost estimation, an improvement in the deadlines planning and the production schedule, a progress in distribution of the workload between the various production workshops, a better knowledge of the individual costs that will permit to reduce the global cost. In order to illustrate our work, we present in this paper three methods to decrease the global cost of a ship. [less ▲] Detailed reference viewed: 110 (23 ULg)Assessment of Ultimate Bending Moment of Ships from a Reliability Point of View, Using Independent Perturbations Method ; ; Caprace, Jean-David et al in Network for Integrating Structural Safety, Risk and Reliability (ASRANet) (2006, July) This paper presents a method to asses hull girder ultimate bending moment distribution, taking into account parameters uncertainty. This method is a part of a research activity carried out at University ... [more ▼] This paper presents a method to asses hull girder ultimate bending moment distribution, taking into account parameters uncertainty. This method is a part of a research activity carried out at University of Liege. The method is able to compute four statistical moments of ultimate strength distribution: average, standard deviation, skewness and kurtosis. Geometry parameters, material parameters and initial imperfections (initial deflections and residual stresses) are considered as random variables and a distribution is associated to each of them. Ultimate bending moment algorithm is a progressive collapse analysis based on Smith method and associated with the load-end shortening model proposed by Bureau Veritas and Joint Bulker Project Rules (JBP). In order to perform a reliability analysis, this algorithm is coupled with independent perturbations method. The advantage is a lower number of simulations compared to the standard Monte-Carlo procedure and a good use of the initial information that is available. The paper contains also a comparative analysis between the presented method and a linear sensitivity analysis performed by the ISSC 2000 “Ultimate Strength” committee for a VLCC structure. [less ▲] Detailed reference viewed: 139 (7 ULg)Ultimate Strength of Stiffened Panels Assessment Taking Into Account Model Uncertainty ; ; Caprace, Jean-David et al in Proceedings of OMAE2006 (2006, June 04) This paper presents a methodology to take into account model uncertainties related to the load-end shortening curve of stiffened panels. This method is a part of a research activity carried out at ... [more ▼] This paper presents a methodology to take into account model uncertainties related to the load-end shortening curve of stiffened panels. This method is a part of a research activity carried out at University of Liège. His goal is to propose a reliability based model to assess hull girder ultimate strength using a progressive collapse algorithm. The numerical results presented here concern the load-shortening model chosen for this research, which is based on Bureau Veritas rules. Model uncertainty is quantified as a parameter considered as a random variable. Four statistical moments (mean, standard deviation, skewness and kurtosis) of this parameter are calculated and analyzed using a data-base of stiffened panels test results published in recent years. In order to increase the number of "actual" values for the statistical assessment, the data-base is completed with non-linear finite element analysis results. The paper contains also some recommendation for the implementation of the proposed method in ultimate strength reliability based analysis. [less ▲] Detailed reference viewed: 59 (6 ULg)An Analytical Cost Assessment Module for the Detailed Design Stage Caprace, Jean-David ; Rigo, Philippe ; Warnotte, Renaud et al in Conference on Computer Applications and Information Technology in the Maritime Industries (COMPIT) (2006, May) The main goal of the project is to implement a “real time” and automatic cost assessment model of the ship hull construction, which integrates the design criteria and production parameters. The presented ... [more ▼] The main goal of the project is to implement a “real time” and automatic cost assessment model of the ship hull construction, which integrates the design criteria and production parameters. The presented method for short-term cost assessment promises to increase the productivity. Nowadays, cost assessment is a key task of an integrated ship design. The various methods to estimate the production cost differs with the required information (input data). The less information is needed, the earlier this method can be used in the design process. The more information is used, the better we can assess the differences between design alternatives. This means: − At the basic design stage: validate the budget and give a reliable bidding price, − At the detailed design stage:, plan the deadlines and establish the production schedule, − At the scheduling production stage: distribute the workload between the various production workshops and assess the productivity. A first prototype of cost assessment module reaches the validation stage at the Alstom Marine St Nazaire shipyard (Chantiers de l’Atlantique) within the framework of the European project InterSHIP which has partly financed the study. In the future, cost assessment will become increasing important. It is proposed to assist/help the designers by a “real time” follow-up of the cost, starting at the earliest conceptual design stage up to the latest detailed design stage. The development such a cost assessment tool requires considering simultaneously the design criteria and the production parameters. Designers will consequently be able to choose the least expensive options at each step of the design procedure (earlier is of course better). [less ▲] Detailed reference viewed: 150 (25 ULg)Optimization of Surface Utilization Using Heuristic Approaches ; Bay, Maud ; Crama, Yves et al in Ship Technology Research = Schiffstechnik (2005), 52(3), 141-147 We present a scheduling problem that arises in factories producing large building blocks. This is a three dimensional bin-packing problem with two spatial dimensions and a time dimension. We propose an ... [more ▼] We present a scheduling problem that arises in factories producing large building blocks. This is a three dimensional bin-packing problem with two spatial dimensions and a time dimension. We propose an algorithm based on the guided local search heuristic of Faroe and al. (Informs Journal of Computing,vol.15, 2003). The algorithm is especially developped to consider real-life issues. Finally the algorithm is applied on an industrial problem and shows excellent performances in speed and quality of the solution. [less ▲] Detailed reference viewed: 114 (30 ULg)Least Construction Cost of FSO Offshore Structures and LNG Gas Carriers Rigo, Philippe ; Matagne, Jérôme ; Caprace, Jean-David in ISOPE, The fifteenth International Offshore and Polar Engineering Conference, Seoul (2005, June 19) In this paper, scantling optimization a FSO offshore structure and a medium size capacity LNG gas carrier are presented. Optmization is based on the LBR5 least cost optimization package. Main originality ... [more ▼] In this paper, scantling optimization a FSO offshore structure and a medium size capacity LNG gas carrier are presented. Optmization is based on the LBR5 least cost optimization package. Main originality and advantage is to combine the minimization of the construction cost with the preliminary design stage. The optimum scantling (least cost) is determined at the earliest design stage, this means before the signature of the contract. Cost savings of 5 to 10% are currently recorded. Relevant information on the methodology and applications to a FSO unit and a LNG carrier are presented in the paper. [less ▲] Detailed reference viewed: 175 (27 ULg)Optimization of Surface Allocation using Heuristic Approaches ; Bay, Maud ; Crama, Yves et al in COMPIT 2005 , Hambourg, Germany (2005, May) In this paper, we present a scheduling problem that arises in factories producing large building blocks (in our case, a shipyard workshop producing prefabricated keel elements). The factory is divided in ... [more ▼] In this paper, we present a scheduling problem that arises in factories producing large building blocks (in our case, a shipyard workshop producing prefabricated keel elements). The factory is divided in several equal size areas. The blocks produced in the factory are very large, and, once a building block is placed in the factory, it cannot be moved until all processes on the building block are finished. The blocks cannot overlap. The objective is to maximize the number of building blocks produced in the factory during a certain time window. To solve this problem, we propose heuristics inspired by techniques initially developed for the three-dimensional bin packing problem, e.g. Faroe and al. (2003), since constraints for both problems are quite similar. Starting from an unfeasible solution, where blocks can overlap, a Guided Local Search (GLS) heuristic is used to minimize the sum of total overlap. If a solution with zero overlap is found, then it is a feasible solution; otherwise the block with the biggest overlap is removed and the procedure is restarted. The GLS algorithm has been improved by Fast Local Search (FST) tech- niques in order to speed up convergence to a local minimum. Additionally, neighborhoods are restricted to their smallest size so as to allow their evaluation in polynomial-time. In a last step, we explain the additional real-life issues arising in the industrial application and how firm-specific constraints can be conveniently considered by the model. [less ▲] Detailed reference viewed: 86 (22 ULg)Modelling, Simulation and Optimization of a Shipbuilding Workshop Bair, Frédéric ; ; Caprace, Jean-David et al in COMPIT'2005 -Conference on Computer Applications and Information Technology in the Maritime Industries, Hamburg (2005, May) Detailed reference viewed: 156 (31 ULg)Rechnergestützte Baukostenschätzung im Schiffsentwurf ; ; Caprace, Jean-David et al in Ship und Hafen (2005), 5 Various approaches for better initial cost estimates for ships are reviewed, compiling recent activities in the USA, Europe and Japan. The trends is towards bottom-up approaches, capable reflecting local ... [more ▼] Various approaches for better initial cost estimates for ships are reviewed, compiling recent activities in the USA, Europe and Japan. The trends is towards bottom-up approaches, capable reflecting local design changes, and simulation based-methods. Coupled to structural computer-aided design programs, these cost estimates modules then allow higher precision for cost estimates even for unconventional ships during early design. [less ▲] Detailed reference viewed: 131 (10 ULg)Cost Assessment in Ship Production ; ; Caprace, Jean-David et al in RINA (2005) Detailed reference viewed: 247 (14 ULg)Recensement et Caractérisation des Pièces Constitutives de la Structure Métallique d'un Navire à Passagers, sous la Double Vision : Produit Fini – Méthode de Production Caprace, Jean-David Master of advanced studies dissertation (2003) Le prix de revient de la structure métallique d'un navire réside principalement dans la main d'oeuvre nécessaire à l'assemblage des pièces et éléments constitutifs. Deux gisements importants de réduction ... [more ▼] Le prix de revient de la structure métallique d'un navire réside principalement dans la main d'oeuvre nécessaire à l'assemblage des pièces et éléments constitutifs. Deux gisements importants de réduction de ce prix sont : - minimiser le coût inhérent à chaque opération (mécanisation, outillages, méthodes, précision, formation ouvrier, ...) ; - minimiser le nombre de ces opérations en diminuant le nombre d'éléments à assembler. Aux Chantiers de l’Atlantique, le premier axe fait depuis plusieurs années l'objet de nombreuses actions et on souhaite aujourd'hui explorer plus avant le second thème. Avant d'envisager la faisabilité et la rentabilité d'actions fortes dans ce domaine, une étape préliminaire visant à établir une connaissance plus fine des éléments constitutifs est nécessaire, c'est à cette première phase que nous avons apporté notre contribution. L’objectif de l'étude est d’établir un recensement et une caractérisation des pièces constitutives de la structure métallique d'un navire à passagers afin de mettre en lumière, le cas échéant, les gisements potentiels d’économie. Deux axes d’études ont été choisis. Le premier s’oriente vers une analyse du « produit fini », le second s’oriente vers la « phase de production ». Il s’agit plus précisément, pour l’analyse du « produit fini » de recenser et caractériser en nombre, en masse, en distribution géographique et en niveau de sollicitation, les pièces constitutives des grandes familles structurelles d’un paquebot de référence choisi parmi les plus récents. Par exemple, il sera question de quantifier le nombre et le poids des pièces constituant les ponts. Par contre, pour l’analyse orientée vers la « phase de production », il s’agit de déterminer et de repérer à quel stade de production les pièces du pont sont montées et vérifier la pertinence de leur lieu de montage. Par exemple, il sera question de quantifier le nombre et le poids des pièces constituants chaque panneau. En final, nous proposons des pistes d’investigation visant à réduire le nombre de pièces constructives s’intégrant dans la structure métallique des paquebots et à en fournir tous les éléments nécessaires à leur analyse. [less ▲] Detailed reference viewed: 64 (8 ULg)Développement et mise au point d’une boucle d’étalonnage pour vanne de régulation en vue d’une future accréditation Caprace, Jean-David Master's dissertation (2002) This project for the graduation of Mechanical Engineer has been realised in the Laboratory for Hydraulic Research of the Ministry of Equipment and Transport of Belgium. It consisted of the design and the ... [more ▼] This project for the graduation of Mechanical Engineer has been realised in the Laboratory for Hydraulic Research of the Ministry of Equipment and Transport of Belgium. It consisted of the design and the realisation of a test bench for hydraulic control valves in preparation for qualified calibration (ISO 17025). Enventually measurement of actual flow characteristics will allow to optimise the use of valves in piping systems. The work has been done in several phases: design, study of metrology, study of standards, implementation and finally preliminary tests and results. The dimensioning of the test bench led to the drawings and draughts of all pipe sections and of the rejection canal (valves with diameter from 100 to 300 mm). The prssure drop has also been evaluated over the whole system. Concerning methodology, measuring techniques were identified, sensors and their signal handling units have been chosen and dimensioned: weirs, pressure sensor, torque meter and electromagnetic flow meter. With the aim to prepare the future qualification of the test bench, existing standards were identified and studied. Their recommendations have been applied where possible. Finally the test bench has been constructed, which has been a rich experience because of the many unexpected problems related to technique as well as to methodology. Preliminary test results for the calibration of a butterfly valve are promising. Nevertheless there is still some work to do before calibration can be qualified. Anyhow the data already collected and the many observations done during these tests were a good opportunity to analyse technological problems and standardisation. So this as a whole results in a data package which can be the base for future projects. [less ▲] Detailed reference viewed: 127 (9 ULg) |
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