Comparison of different Multiple-criteria decision analysis methods in the context of conceptual design: application to the development of a solar collector structure

At each stage of the product development process, the designers are facing an important task which consists of decision making. Two cases are observed: the problem of concept selection in conceptual design phases and, the problem of pre-dimensioning once concept choices are made. Making decisions in conceptual design phases on a sound basis is one of the most difficult challenges in engineering design, especially when innovative concepts are introduced. On the one hand, designers deal with imprecise data about design alternatives. On the other hand, design objectives and requirements are usually not clear in these phases. The greatest opportunities to reduce product life cycle costs usually occur during the first conceptual design phases. The need for reliable multi-criteria decision aid (MCDA) methods is thus greatest at early conceptual design phases. Various MCDA methods are proposed in the literature. The main criticism of these methods is that they usually yield different results for the same problem. In this work, an analysis of six MCDA methods (weighed sum, weighted product, Kim & Lin, compromise programming, TOPSIS, and ELECTRE I) was conducted. Our analysis was performed via an industrial case of solar collector structure development. The objective is to define the most appropriate MCDA methods in term of three criteria: (i) the consistency of the results, (ii) the ease of understanding and, (iii) the adaptation of the decision type. The results show that TOPSIS is the most consistent MCDA method in our case

Critical review of multi-criteria decision aid methods in conceptual design phases: application to the development of a solar collector structure

At each stage of the product development process, the designers are facing an important task which consists of decision making. Two cases are observed: the problem of concept selection in conceptual design phases and, the problem of pre-dimensioning once concept choices are made. Making decisions in conceptual design phases on a sound basis is one of the most difficult challenges in engineering design, especially when innovative concepts are introduced. On the one hand, designers deal with imprecise data about design alternatives. On the other hand, design objectives and requirements are usually not clear in these phases. The greatest opportunities to reduce product life cycle costs usually occur during the first conceptual design phases. The need for reliable multi-criteria decision aid (MCDA) methods is thus greatest at early conceptual design phases. Various MCDA methods are proposed in the literature. The main criticism of these methods is that they usually yield different results for the same problem [22,23,25]. In this work, an analysis of six MCDA methods (weighed sum, weighted product, Kim & Lin, compromise programming, TOPSIS, and ELECTRE I) was conducted. Our analysis was performed via an industrial case of solar collector structure development. The objective is to define the most appropriate MCDA methods in term of three criteria: (i) the consistency of the results, (ii) the ease of understanding and, (iii) the adaptation of the decision type. The results show that TOPSIS is the most consistent MCDA method in our case

Intégration de la maturité des connaissances dans la prise de décision en conception mécanique : application à un système solaire.

The successful development of industrial products has a considerable economic challenge for the company. Decisions on concepts and product architecture have a significant impact on the overall cost of the product life cycle. Manufacturers are then increasingly encouraged to adopt methods to streamline design decisions. These methods must be consistent with the level of knowledge acquired on alternative design, the nature of decision making and assessment tools available. Thus, both methods of decision support have been developed in this thesis based on the study design phase.A first method is proposed for the upstream design stage in which the goal of the company is to reduce the number of concepts initially proposed to focus its efforts and resources on the most promising concepts. During this phase, the products are defined very loosely. Designers must then make a lot of assumptions when proposing role models to assess the concepts. These models, which express a knowledge of explicit nature, are insufficient to make choices concepts. To overcome this difficulty, we are moving in our study to the implicit knowledge (or subjective), obtained through the experience and expertise acquired by the designers. To integrate this knowledge in decision-making, it is first formalized through tools such as preferably functions. The overall approach to decision support proposed for combining both the implicit knowledge and explicit knowledge (represented by the role models) to assess each concept in terms of ability to meet the minimum requirements for validation and level fitness with the design goals. The objectives and preferences of decision makers are, in turn, structured and formalized through the OIA model (Observation-Interpretation-Aggregation) previously developed in the laboratory I2M-BMI.A second method was proposed for the downstream design phase that aims to set the parameters of the final product (choice of materials, dimensions, etc.) after the concept was chosen. During this phase, the product is defined in a more precise manner and behavior patterns are more representative of the relevant physical phenomena of the concept studied. These models are however based on assumptions which sometimes lead to a questioning their accuracy, especially for some design parameters. Fix the product parameters based solely on these patterns of behavior requires taking into account their accuracy level. We have therefore developed an accuracy indicator of these models that integrates on the one hand, an objective assessment which is the measure of difference between the model and a reference behavior (assumed correct) and, secondly, on a subjective assessment that is based on the distance measurement with the reference solution (prototyped solution) and trusts functions established by the designers. The combination of objective and subjective assessment of the accuracy provides at the end a general indicator of accuracy able to cover the entire design space. The indicator thus obtained is used in a method of decision support that qualifies each candidate solution in terms of risk posed by the accuracy of the models and level of satisfaction of design objectives (based the model OIA) .La réussite du développement des produits industriels a un enjeu économique considérable pour l’entreprise. Les décisions sur les concepts et sur l’architecture du produit ont un impact considérable sur le coût global du cycle de vie du produit. Les industriels sont alors de plus en plus encouragés à adopter des méthodes permettant de rationaliser les décisions de conception. Ces méthodes doivent être en adéquation avec le niveau de connaissance acquis sur les alternatives de conception, la nature des décisions à prendre et les outils d’évaluation disponibles. Ainsi, deux méthodes d’aide à la décision ont été développées dans cette thèse en fonction de la phase de conception étudiée.Une première méthode est proposée pour la phase amont de conception dans laquelle l’objectif de l’entreprise est de réduire le nombre de concepts proposés initialement pour concentrer ses efforts et ses ressources sur les concepts les plus prometteurs. Durant cette phase, les produits sont définis d’une manière très imprécise. Les concepteurs doivent alors faire beaucoup d'hypothèses lorsqu’ils proposent des modèles de comportement destinés à évaluer les concepts. Ces modèles, qui expriment une connaissance de nature explicite, sont insuffisants pour faire des choix de concepts. Pour remédier à cette difficulté, nous nous orientons dans notre étude vers la connaissance implicite (ou subjective), obtenue au travers de l'expérience et du savoir-faire acquis par les concepteurs. Afin d’intégrer cette connaissance dans la prise de décision, elle est d’abord formalisée au travers d’outils comme les fonctions de préférence. La méthode globale d’aide à la décision proposé permet de combiner à la fois cette connaissance implicite et la connaissance explicite (représentée par les modèles de comportement) pour évaluer chaque concept en termes d’aptitude à respecter les exigences minimales de validation et du niveau d’adéquation avec les objectifs de conception. Les objectifs et préférences des décideurs sont, quant à eux, structurés et formalisés au travers du modèle OIA (Observation-Interprétation-Agrégation) développé auparavant dans le laboratoire I2M-IMC.Une deuxième méthode a été proposée pour la phase aval de conception qui a pour objectif de fixer les paramètres du produit final (choix des matériaux, dimensions, etc.) après que le concept ait été choisi. Durant cette phase, le produit est défini d’une manière plus précise et les modèles de comportement sont plus représentatifs des phénomènes physiques pertinents du concept étudié. Ces modèles restent cependant basés sur des hypothèses qui conduisent parfois à une remise en question de leur exactitude, surtout pour certains paramètres de conception. Fixer les paramètres du produit en se basant uniquement sur ces modèles de comportement nécessite la prise en compte de leur niveau exactitude. Nous avons donc développé un indicateur d’exactitude de ces modèles qui intègre, d’une part, une évaluation objective qui est la mesure d’écart entre le modèle et un comportement de référence (supposé exact) et, d’autre part, sur une évaluation subjectif qui se base sur la mesure de distance avec la solution de référence (solution prototypée) et sur des fonctions de confiances établies par les concepteurs. La combinaison d’une évaluation objective et subjective de l’exactitude permet d’obtenir à la fin un indicateur général d’exactitude capable de couvrir l’intégralité de l’espace de conception. L’indicateur ainsi obtenu est utilisé dans une méthode d’aide à la décision qui qualifie chaque solution candidate en terme de risque engendré par les l’exactitude des modèles et de degré de satisfaction des objectifs de conception (en se basant la modèle OIA)

Endovascular treatment of acute aortic isthmian ruptures: case study

Traumatic rupture of the aortic isthmus is a rare lesion occurring in patients subjected to violent deceleration. Because of the forces involved, it is frequently associated with concomitant life-threatening injuries. The endovascular intervention has been described to be a feasible and efficient technique which may be proposed as a therapeutic option for patients with multiple traumas instead of delayed classical surgical repair after stabilization. We report the case of an adult who has had an accident with a traumatic rupture of the aortic isthmus associated with other lesions, our patient received endovascular treatment. The aortic prosthesis was imported from France and the surgery was done 3 days after the patient's admission. This procedure was performed for the first time in Morocco in our hospital with a multidisciplinary team. The prosthesis was implemented successfully and the result was very satisfactory on the heart level.Keywords: Endovascular treatment, aortic isthmian ruptures, endovascular prosthesi

Early environmental assessment of products using behavior models and the impact of their inaccuracy on environmental product performance

The decisions made during the preliminary design phases considerably impact the development of a product's lifecycle, acting on its environmental performance, cost, and duration of its realization. However, the lack of relevant information during these phases does not allow for the accurate evaluation of design solutions. In addition, it generates schedule delays and overruns in the budget allocated to developing a given solution. In this perspective, the present work aims to assess the accuracy of the behavior models used for exploring solutions during the embodiment phase. This was based on two measures of different nature, namely objective accuracy, which is evaluated by referring to real prototyping of a given solution, and the subjective accuracy measure, which allows to the expression of the degradation of the first measure in relation to the reference point. This combination will lead to a measure that can be generalized on all the design space. In a second step, the current work suggests an estimation of the effect of these models' accuracy on the proposed solutions' environmental impact. To this end, a sensitivity study was carried out on the input data of the model (design parameters) in order to deduce the effect of the results obtained (performance parameters) on the mass and, consequently, the environmental impact of the solution. In order to highlight the approach adopted in the present study, it was applied to a real industrial case, ultimately leading to the most optimized solution in terms of accuracy and environmental impact

Exploring design space in embodiment design with consideration of models accuracy

Rework tasks in collaborative development projects dealing with immature design concepts are very frequent and are responsible of cost overruns and schedule delays. Taking into account uncertainty and accuracy of models (and data) improves decision making according to strategic orientation for product development. Based on a real design of light, slender but rigid collectors’ supports, multiple tools have been developed and tested to support decision making at different stages of development process. The objective of this paper is to investigate the integration of these accuracy evaluations into the design process. This proposal is validated by the industrial development and validation.Projet SOLR

Exploring design space in embodiment design with consideration of models accuracy

Rework tasks in collaborative development projects dealing with immature design concepts are very frequent and are responsible of cost overruns and schedule delays. Taking into account uncertainty and accuracy of models (and data) improves decision making according to strategic orientation for product development. Based on a real design of light, slender but rigid collectors’ supports, multiple tools have been developed and tested to support decision making at different stages of development process. The objective of this paper is to investigate the integration of these accuracy evaluations into the design process. This proposal is validated by the industrial development and validation

Mixed neuroendocrine-non-neuroendocrine neoplasms of the right colon: a case report

Mixed neuroendocrine-non neuroendocrine neoplasm (MiNENs) is a rare gastrointestinal neoplasm that has been redefined by the World Health Organization (WHO) in 2017 as the association of two types of components, neuroendocrine and non-neuroendocrine, each of them present in at least 30% of the tumour mass. Small case reports and case series have demonstrated the occurrence of this neoplasm in the colon. We here report the case of a 47-year-old man undergoing colonscopy for anemia. This showed impassable polypoidal tumor budding in the right colic flexure. Computerized tomography (CT) scan and magnetic resonance imaging (MRI) showed the presence of liver metastases. As the tumor was hemorrhagic, right hemicolectomy with lymph node dissection was performed. The histological examination showed MiNEN of the ascending colon. The patient received adjuvant chemotherapy

Luxation antéro-supérieure de l´épaule: à propos d´un cas et revue de la littérature

Les luxations traumatiques de l'articulation de l'épaule sont généralement décrites comme des luxations antéro-inférieures. Les luxations antéro-supérieures sont extrêmement rares. Nous rapportons un cas rare de luxation traumatique de l´épaule antéro-supérieure chez un patient âgé de 45 ans où l´examen physique trouve une saillie antéro-superieure de la tête humérale en sous-cutanée avec comblement de l´espace sous acromiale, le diagnostic était confirmé radiologiquement avec la découverte d´une rupture totale des tendons supra-épineux et sous scapulaire à l´imagerie par résonance magnétique. L´épaule était jugée instable après réduction de la luxation. Une arthrorise gléno-humérale provisoire était réalisée par la suite avec des bons résultats fonctionnels

Glomérulonéphrite extra-membraneuse et syndrome myélodysplasique: une association rare

Les syndromes myélodysplasiques peuvent s’accompagner de maladies auto-immunes. L’atteinte rénale au cours de ces syndromes est rare. Dans ce cas, les glomérulopathies prédominent cette atteinte. La glomérulonéphrite extra-membraneuse est exceptionnellement reportée en association avec un syndrome myélodysplasique. Nous rapportons dans ce papier le cas d’une patiente présentant une glomérulonéphrite associée à une anémie révélant un syndrome myélodysplasique de faible risque. Dans la lumière de ce cas, nous faisons une courte revue de la littérature des cas précédemment publiés et nous discutons le lien pathogénique entre ces deux entités