The Experts below are selected from a list of 136281 Experts worldwide ranked by ideXlab platform
Roxane Pouliot - One of the best experts on this subject based on the ideXlab platform.
-
Application of an In Vitro Psoriatic Skin Model to Study Cutaneous Metabolization of Tazarotene
Processes, 2019Co-Authors: Alexandre Morin, Mélissa Simard, Geneviève Rioux, Alexe Grenier, Sophie Morin, Roxane PouliotAbstract:Psoriasis is an inflammatory Skin disease characterized by the presence of whitish and scaly plaques, which can cover up to 90% of the body surface. These plaques result from the hyperproliferation and abnormal differentiation of keratinocytes. Dermopharmaceutical testing of new therapies is limited by healthy and pathological Skin Models, which are not closely enough mimicking their in vivo counterparts. In this study, we exploited percutaneous absorption and Ultra Performance Liquid Chromatography (UPLC) analyses in order to determine the metabolic capacity of our psoriatic Skin Model. Skin substitutes were reconstructed according to the self-assembly method and tested regarding their percutaneous absorption of a topical formulation of tazarotene, followed by UPLC analyses. Histological and immunofluorescence analyses confirmed both the healthy and psoriatic phenotypes. Results from percutaneous absorption showed a significant level of tazarotene metabolite (tazarotenic acid) when the formulation was applied over 24 h on the Skin substitutes. The presence of tazarotenic acid in the dermis and the epidermis of healthy and psoriatic Skin substitutes confirms the metabolic capacity of both Skin Models, and thereby their ability to screen new molecules with antipsoriatic potential. In conclusion, the present data suggest that our psoriatic Skin Model could possibly be used in clinic to screen in vitro responses of patient to a panel of drugs without having them experiencing the drawback of each drug.
-
development of an in vitro psoriatic Skin Model by tissue engineering
Journal of Dermatological Science, 2009Co-Authors: Jessica Jean, Marc Lapointe, Jacques Soucy, Roxane PouliotAbstract:Summary Background Psoriasis is a chronic Skin disease characterized by a thickening and disorganization of the Skin's protective barrier. Objectives This study aims to develop and characterize a novel in vitro psoriatic human Skin Model produced by tissue engineering. Methods The self-assembly method, a tissue engineering approach based on the capacity of mesenchymal cells, such as fibroblasts, to create their own extracellular matrix in vitro , was used to create our substitutes. Manipulatable sheets of fibroblasts were superimposed creating a new dermis upon which keratinocytes are seeded, leading to a complete bilayered Skin substitute. The characterization of the psoriatic substitutes was performed by macroscopic, histological and immunohistochemical analyses and contrasted to those constructed from healthy cells. Results Macroscopically, the psoriatic substitutes were more white and thicker than the healthy substitutes. The histological analysis of psoriatic substitutes stained with Masson's trichrome revealed a characteristic thickening of the epidermal layer seen in psoriatic Skin in vivo . Immunohistochemical analysis of the psoriatic substitutes showed, among other things, an overexpression of involucrin and an underexpression of filaggrin and loricrin. Conclusion These data suggest that the macroscopic, histological and immunohistochemical characteristics of psoriasis are partially retained in the substitutes, thus providing a good Model to investigate the mechanisms of abnormal keratinocyte growth and to study cell–cell interactions.
Nabil Anwer - One of the best experts on this subject based on the ideXlab platform.
-
Skin Model Shapes for multi-stage manufacturing in single-part production
Procedia CIRP, 2020Co-Authors: Robert Hofmann, Sophie Gröger, Nabil AnwerAbstract:Abstract Geometrical features are fundamental elements for the fulfilment of the functional product requirements. Therefore, their inevitable deviations caused by manufacturing inaccuracies are the main issues in the field of tolerance management. To close the gap between physical part description and nominal Model representation, the framework of discrete geometrical representatives via Skin Model Shapes has been developed and continuously enhanced. As the underlying concepts are based on final virtual parts, consistent inferences to every single manufacturing step are not fully investigated in literature. This paper presents the development of Skin Model Shapes based on the virtual representation of intermediate part outcome (in-process geometry) and the integration of machining processes. Thus, integration and simulation of different kinds of deviations are enabled at each manufacturing stage considering error accumulation due to machine specific inaccuracies, such as tool movement and fixturing. Furthermore, the effect of inaccuracies on the final conformance result can be quantified at each manufacturing stage. A case study is presented to illustrate the entire approach and to demonstrate the validity of the proposed methods.
-
Integration of Thermal Effects into Tolerancing Using Skin Model Shapes
Procedia CIRP, 2016Co-Authors: Orzuri Rique Garaizar, Lihong Qiao, Nabil Anwer, Luc MathieuAbstract:The integration of more physical properties into the Skin Model is fundamental for extending the tolerancing process to the different phases of the product lifecycle. This paper presents a study of the deformation effects on the Skin Model provoked by the thermal and working environment of the workpiece. The proposed methodology departs from the Skin Model at room temperature, and generates Skin Model Shapes by performing a Finite Element Analysis (FEA). The simulation tool has been successfully tested in the study of a practical industrial application, a gas turbine blade, which combines many of the nowadays challenges of CAD, FEA and CAT.
-
Status and Prospects of Skin Model Shapes for Geometric Variations Management
Procedia CIRP, 2016Co-Authors: Benjamin Schleich, Luc Mathieu, Nabil Anwer, Sandro WartzackAbstract:Geometric part deviations, which are inevitably observed on every manufactured workpiece, have distinct effects on the assemblability as well as on the function and quality of physical artefacts. As a consequence, geometric variations management is an important issue for manufacturing companies. However, assessing the effects of form deviations already in virtual product realization remains an important challenge. This paper illustrates and summarizes the current status and development trends of the Skin Model Shape paradigm, which provides an operationalization and a digital representation of the Skin Model concept for Modelling product shape variability and hence may serve as a comprehensive Model for computer-aided variations management.
-
An Improved Tolerance Analysis Method Based on Skin Model Shapes of Planar Parts
Procedia CIRP, 2016Co-Authors: Zuowei Zhu, Lihong Qiao, Nabil AnwerAbstract:Abstract Geometric deviations have huge influences on the functional behavior of product, which should be analyzed and properly controlled. Tolerance analysis, as a way to evaluate geometric deviations, is an essential part of product development. Current Computer Aided Tolerancing systems provide solutions for tolerance analysis but have limitations in the consideration of form deviations. The Skin Model theory, as a new research topic, represents part with non-ideal Model that comprises geometric deviations, thus developing into a new computer aided tolerancing approach. In this paper, the related work with respect to the generation of Skin Model Shapes and its application in assembly simulation and tolerance analysis is briefly introduced. In order to overcome its shortcomings in the tolerance analysis employing SMSs, this paper proposes an improved method by taking advantage of the method adopted in a CAT system. The proposed method supports the analysis of position and orientation tolerances and has been proved to be valid through a case study.
-
Contact and Mobility Simulation for Mechanical Assemblies Based on Skin Model Shapes
Journal of Computing and Information Science in Engineering, 2015Co-Authors: Benjamin Schleich, Luc Mathieu, Nabil Anwer, Sandro WartzackAbstract:Assembly Modelling as one of the most important steps in the product development activity relies more and more on the extensive use of CAD systems. The Modelling of geometric interfaces between the components of the assembly is of central importance in the simulation of mechanical assemblies. Over the past decades, many researchers have devoted their efforts to establish theories and systems covering assembly Modelling. Although the product form or shape have been extensively investigated considering the nominal CAD geometry, inevitable limitations can be reported. Computer Aided Tolerancing systems provide simulation tools for Modelling the effects of tolerances on the assembly but still lack of form deviation considerations. The Skin Model concept which stemmed from the theoretical foundations of Geometrical Product Specification and Verification (GPS) has been developed to enrich the nominal geometry considering realistic physical shapes. However, the digital representation of the Skin Model has been investigated only recently. This paper presents a novel approach for a Skin Model based simulation of contact and mobility for assemblies. Three important issues are addressed: the geometric Modelling of the contact, the contact quality evaluation, and the motion analysis. The main contribution to computer aided tolerancing can be found in the analysis of the effects of geometric form deviations on the assembly and motion behaviour of solid mechanics, which comprises Models for the assembly simulation, for the contact quality evaluation, and for the motion analysis. A case study is presented to illustrate the proposed approaches.
Luc Mathieu - One of the best experts on this subject based on the ideXlab platform.
-
Integration of Thermal Effects into Tolerancing Using Skin Model Shapes
Procedia CIRP, 2016Co-Authors: Orzuri Rique Garaizar, Lihong Qiao, Nabil Anwer, Luc MathieuAbstract:The integration of more physical properties into the Skin Model is fundamental for extending the tolerancing process to the different phases of the product lifecycle. This paper presents a study of the deformation effects on the Skin Model provoked by the thermal and working environment of the workpiece. The proposed methodology departs from the Skin Model at room temperature, and generates Skin Model Shapes by performing a Finite Element Analysis (FEA). The simulation tool has been successfully tested in the study of a practical industrial application, a gas turbine blade, which combines many of the nowadays challenges of CAD, FEA and CAT.
-
Status and Prospects of Skin Model Shapes for Geometric Variations Management
Procedia CIRP, 2016Co-Authors: Benjamin Schleich, Luc Mathieu, Nabil Anwer, Sandro WartzackAbstract:Geometric part deviations, which are inevitably observed on every manufactured workpiece, have distinct effects on the assemblability as well as on the function and quality of physical artefacts. As a consequence, geometric variations management is an important issue for manufacturing companies. However, assessing the effects of form deviations already in virtual product realization remains an important challenge. This paper illustrates and summarizes the current status and development trends of the Skin Model Shape paradigm, which provides an operationalization and a digital representation of the Skin Model concept for Modelling product shape variability and hence may serve as a comprehensive Model for computer-aided variations management.
-
The Skin Model : a fundamental concept for product specification and verification
2016Co-Authors: Luc MathieuAbstract:In modern production engineering, new complex products with controlled tolerances are being increasingly adopted to improve companies’ market position. Geometrical variations are inevitably generated during the manufacturing stage due to the limited accuracy of manufacturing technologies. Within the context of Product Lifecycle Management (PLM), information communication and sharing requires to manage the geometrical variations along the whole product lifecycle. The geometrical variations should be considered early in the tolerancing process in the design stage. Different concepts have been proposed to build coherent and complete tolerancing processes along the whole product lifecycle. Among them, GeoSpelling proposed by Ballu and Mathieu in 1995, as the basis of the actual Geometrical Product Specification (GPS) standards, enables a comprehensive Modelling framework and an unambiguous language to describe geometrical variations covering the overall product life cycle thanks to a set of objects as features, operations and characteristics based on the fundamental concept of the “Skin Model”. The Skin Model concept is the basic concept of GeoSpelling. It is an abstract Model of the physical interface between a workpiece and its environment. Different from the nominal Model, which is deemed as an ideal feature, the Skin Model is a shape Model to describe the non-perfect shapes. In GeoSpelling, a specification is as a condition on a characteristic defined from geometric features, which are created from a Skin Model by different operations (partition, extraction, filtration, association, collection and construction). To be able to understand the meaning of a specification based on this definition, a tool called GPS card has been created. This tool considers every type of specifications, for isolated parts and for assemblies. This tool also compensates the contradictions and lacks of current ISO GPS standards. It is a very useful tool for inspection and industrial measurement activities. It permits to define without ambiguity the characteristic to be measured. Geospelling is able to express clearly the measurand and the sequence of operations with the same language used for the specification. It is what ISO 213 calls the Duality principal. This approach helps inspection people to highlights the method uncertainty, the difference between the characteristic to be measured and the measurand. The concept of the Skin Model has been initially created for describing without ambiguity the quantity to be measured. After the choose by ISO, as starting point for creating new standards in the field of Specification and Verification and fifteen years later, the idea was to create digital Skin Models for simulation and visualisation. This idea was to operationalize GeoSpelling on both nominal Model and Skin Model. However, this operationalization has not been successfully completed in a digital manner and few research studies have focused on the Skin Model representation and simulation. As a response, the concept of Skin Model Shapes has been developed as a novel approach for the consideration of product shape variability. It employs discrete geometry methods and computational techniques, such as point clouds, surface meshes and geometric processing, to Model shape variability and to facilitate the communication of geometric product information throughout the product design, manufacturing, and inspection processes. Suitable representation methods should be carefully considered for different purposes. A shape representation scheme can be defined as a mapping from a computer structure to a well-defined mathematical Model, which defines the notion of the physical object in terms of computable mathematical properties and is independent of any particular representation scheme. Skin Model Shapes, which are particular Skin Model representatives from a simulation perspective, are generated. In this regard, a Skin Model Shape is a specific outcome of the conceptual Skin Model and comprises deviations from manufacturing and assembly. The process for generating Skin Model Shapes is split into a prediction and an observation stages with respect to the available information and knowledge about expected geometric deviations. This talk highlights the foundations of the concept of Skin Model and its potentials for the representation of product geometry considering geometric variations along the product lifecycle, and illustrates main applications in the context of product and process development.
-
Contact and Mobility Simulation for Mechanical Assemblies Based on Skin Model Shapes
Journal of Computing and Information Science in Engineering, 2015Co-Authors: Benjamin Schleich, Luc Mathieu, Nabil Anwer, Sandro WartzackAbstract:Assembly Modelling as one of the most important steps in the product development activity relies more and more on the extensive use of CAD systems. The Modelling of geometric interfaces between the components of the assembly is of central importance in the simulation of mechanical assemblies. Over the past decades, many researchers have devoted their efforts to establish theories and systems covering assembly Modelling. Although the product form or shape have been extensively investigated considering the nominal CAD geometry, inevitable limitations can be reported. Computer Aided Tolerancing systems provide simulation tools for Modelling the effects of tolerances on the assembly but still lack of form deviation considerations. The Skin Model concept which stemmed from the theoretical foundations of Geometrical Product Specification and Verification (GPS) has been developed to enrich the nominal geometry considering realistic physical shapes. However, the digital representation of the Skin Model has been investigated only recently. This paper presents a novel approach for a Skin Model based simulation of contact and mobility for assemblies. Three important issues are addressed: the geometric Modelling of the contact, the contact quality evaluation, and the motion analysis. The main contribution to computer aided tolerancing can be found in the analysis of the effects of geometric form deviations on the assembly and motion behaviour of solid mechanics, which comprises Models for the assembly simulation, for the contact quality evaluation, and for the motion analysis. A case study is presented to illustrate the proposed approaches.
-
Skin Model shapes a new paradigm shift for geometric variations Modelling in mechanical engineering
Computer-aided Design, 2014Co-Authors: Benjamin Schleich, Luc Mathieu, Nabil Anwer, Sandro WartzackAbstract:Geometric deviations are inevitably observable on manufactured workpieces and have huge influences on the quality and function of mechanical products. Therefore, many activities in geometric variations management have to be performed to ensure the product function despite the presence of these deviations. Dimensional and Geometrical Product Specification and Verification (GPS) are standards for the description of workpieces. Their lately revision grounds on GeoSpelling, which is a univocal language for geometric product specification and verification and aims at providing a common understanding of geometric specifications in design, manufacturing, and inspection. The Skin Model concept is a basic concept within GeoSpelling and is an abstract Model of the physical interface between a workpiece and its environment. In contrast to this understanding, established Models for computer-aided Modelling and engineering simulations make severe assumptions about the workpiece surface. Therefore, this paper deals with operationalizing the Skin Model concept in discrete geometry for the use in geometric variations management. For this purpose, Skin Model Shapes, which are particular Skin Model representatives from a simulation perspective, are generated. In this regard, a Skin Model Shape is a specific outcome of the conceptual Skin Model and comprises deviations from manufacturing and assembly. The process for generating Skin Model Shapes is split into a prediction and an observation stage with respect to the available information and knowledge about expected geometric deviations. Moreover, applications for these Skin Model Shapes in the context of mechanical engineering are given.
Sandro Wartzack - One of the best experts on this subject based on the ideXlab platform.
-
Status and Prospects of Skin Model Shapes for Geometric Variations Management
Procedia CIRP, 2016Co-Authors: Benjamin Schleich, Luc Mathieu, Nabil Anwer, Sandro WartzackAbstract:Geometric part deviations, which are inevitably observed on every manufactured workpiece, have distinct effects on the assemblability as well as on the function and quality of physical artefacts. As a consequence, geometric variations management is an important issue for manufacturing companies. However, assessing the effects of form deviations already in virtual product realization remains an important challenge. This paper illustrates and summarizes the current status and development trends of the Skin Model Shape paradigm, which provides an operationalization and a digital representation of the Skin Model concept for Modelling product shape variability and hence may serve as a comprehensive Model for computer-aided variations management.
-
Approaches for the assembly simulation of Skin Model shapes
Computer-aided Design, 2015Co-Authors: Benjamin Schleich, Sandro WartzackAbstract:Even though they are weakly noticed, geometric part deviations accompany our everyday life. These geometric deviations affect the assemblability and functional compliance of products, since small part variations accumulate through large-scale assemblies and lead to malfunction as well as decreased product reliability and safety. However, the consideration of part deviations in the virtual Modelling of mechanical assemblies is an ongoing challenge in computer-aided tolerancing research. This is because the resulting assembly configurations for variant parts are far more complicated than for nominal assemblies. In this contribution, two approaches for the relative positioning of point based Models are highlighted and adapted to the assembly simulation of Skin Model Shapes, which are specific workpiece representatives considering geometric deviations. The first approach employs constrained registration techniques to determine the position of variant parts in an assembly considering multiple assembly steps simultaneously, whereas the second utilizes the difference surface to solve the positioning problem sequentially. The application of these approaches to computer-aided tolerancing is demonstrated, though their applicability reaches various fields of industrial geometry. Skin Model Shapes are digital part representatives comprising geometric deviations.Approaches for the relative positioning of point-based Skin Model Shapes are proposed.The approaches ground on algorithms from computational geometry and computer graphics.Applications for the assembly simulation in tolerancing are given.
-
Contact and Mobility Simulation for Mechanical Assemblies Based on Skin Model Shapes
Journal of Computing and Information Science in Engineering, 2015Co-Authors: Benjamin Schleich, Luc Mathieu, Nabil Anwer, Sandro WartzackAbstract:Assembly Modelling as one of the most important steps in the product development activity relies more and more on the extensive use of CAD systems. The Modelling of geometric interfaces between the components of the assembly is of central importance in the simulation of mechanical assemblies. Over the past decades, many researchers have devoted their efforts to establish theories and systems covering assembly Modelling. Although the product form or shape have been extensively investigated considering the nominal CAD geometry, inevitable limitations can be reported. Computer Aided Tolerancing systems provide simulation tools for Modelling the effects of tolerances on the assembly but still lack of form deviation considerations. The Skin Model concept which stemmed from the theoretical foundations of Geometrical Product Specification and Verification (GPS) has been developed to enrich the nominal geometry considering realistic physical shapes. However, the digital representation of the Skin Model has been investigated only recently. This paper presents a novel approach for a Skin Model based simulation of contact and mobility for assemblies. Three important issues are addressed: the geometric Modelling of the contact, the contact quality evaluation, and the motion analysis. The main contribution to computer aided tolerancing can be found in the analysis of the effects of geometric form deviations on the assembly and motion behaviour of solid mechanics, which comprises Models for the assembly simulation, for the contact quality evaluation, and for the motion analysis. A case study is presented to illustrate the proposed approaches.
-
Skin Model shapes a new paradigm shift for geometric variations Modelling in mechanical engineering
Computer-aided Design, 2014Co-Authors: Benjamin Schleich, Luc Mathieu, Nabil Anwer, Sandro WartzackAbstract:Geometric deviations are inevitably observable on manufactured workpieces and have huge influences on the quality and function of mechanical products. Therefore, many activities in geometric variations management have to be performed to ensure the product function despite the presence of these deviations. Dimensional and Geometrical Product Specification and Verification (GPS) are standards for the description of workpieces. Their lately revision grounds on GeoSpelling, which is a univocal language for geometric product specification and verification and aims at providing a common understanding of geometric specifications in design, manufacturing, and inspection. The Skin Model concept is a basic concept within GeoSpelling and is an abstract Model of the physical interface between a workpiece and its environment. In contrast to this understanding, established Models for computer-aided Modelling and engineering simulations make severe assumptions about the workpiece surface. Therefore, this paper deals with operationalizing the Skin Model concept in discrete geometry for the use in geometric variations management. For this purpose, Skin Model Shapes, which are particular Skin Model representatives from a simulation perspective, are generated. In this regard, a Skin Model Shape is a specific outcome of the conceptual Skin Model and comprises deviations from manufacturing and assembly. The process for generating Skin Model Shapes is split into a prediction and an observation stage with respect to the available information and knowledge about expected geometric deviations. Moreover, applications for these Skin Model Shapes in the context of mechanical engineering are given.
-
From solid Modelling to Skin Model shapes: Shifting paradigms in computer-aided tolerancing
Cirp Annals-manufacturing Technology, 2014Co-Authors: Nabil Anwer, Benjamin Schleich, Luc Mathieu, Sandro WartzackAbstract:Abstract Product design requires the consideration of geometric Models and representations that reflect shape deviations and support tolerance management issues. Computer-Aided Tolerancing (CAT) systems have been developed as simulation tools for Modelling the effects of tolerances on digital product simulation. However, geometric variations cannot be addressed efficiently with regard to form deviations. This paper investigates the concepts of Skin Model Shapes, which provide a finite describability and the digital representation of the Skin Model concept, and their unified discrete geometry representation. New contributions to tolerance representation and analysis are presented. Applications and perspectives for CAT systems are highlighted as well.
Jessica Jean - One of the best experts on this subject based on the ideXlab platform.
-
development of an in vitro psoriatic Skin Model by tissue engineering
Journal of Dermatological Science, 2009Co-Authors: Jessica Jean, Marc Lapointe, Jacques Soucy, Roxane PouliotAbstract:Summary Background Psoriasis is a chronic Skin disease characterized by a thickening and disorganization of the Skin's protective barrier. Objectives This study aims to develop and characterize a novel in vitro psoriatic human Skin Model produced by tissue engineering. Methods The self-assembly method, a tissue engineering approach based on the capacity of mesenchymal cells, such as fibroblasts, to create their own extracellular matrix in vitro , was used to create our substitutes. Manipulatable sheets of fibroblasts were superimposed creating a new dermis upon which keratinocytes are seeded, leading to a complete bilayered Skin substitute. The characterization of the psoriatic substitutes was performed by macroscopic, histological and immunohistochemical analyses and contrasted to those constructed from healthy cells. Results Macroscopically, the psoriatic substitutes were more white and thicker than the healthy substitutes. The histological analysis of psoriatic substitutes stained with Masson's trichrome revealed a characteristic thickening of the epidermal layer seen in psoriatic Skin in vivo . Immunohistochemical analysis of the psoriatic substitutes showed, among other things, an overexpression of involucrin and an underexpression of filaggrin and loricrin. Conclusion These data suggest that the macroscopic, histological and immunohistochemical characteristics of psoriasis are partially retained in the substitutes, thus providing a good Model to investigate the mechanisms of abnormal keratinocyte growth and to study cell–cell interactions.
