The Experts below are selected from a list of 49422 Experts worldwide ranked by ideXlab platform
Pierre Seppecher - One of the best experts on this subject based on the ideXlab platform.
-
Structural Optimization of Thin Elastic Plates: The Three Dimensional Approach
Archive for Rational Mechanics and Analysis, 2011Co-Authors: Guy Bouchitté, Ilaria Fragalà, Pierre SeppecherAbstract:The natural way to find the most compliant design of an elastic plate is to consider the three-dimensional elastic structures which minimize the work of the loading term, and pass to the limit when the thickness of the design region tends to zero. In this paper, we study the asymptotics of such a Compliance Problem, imposing that the volume fraction remains fixed. No additional topological constraint is assumed on the admissible configurations. We determine the limit Problem in different equivalent formulations, and we provide a system of necessary and sufficient optimality conditions. These results were announced in Bouchitté et al. (C. R. Acad. Sci. Paris, Ser. I. 345:713–718, 2007). Furthermore, we investigate the vanishing volume fraction limit, which turns out to be consistent with the results in Bouchitté and Fragalà (Arch. Rat. Mech. Anal. 184:257–284, 2007; SIAM J. Control Optim. 46:1664–1682, 2007). Finally, some explicit computation of optimal plates are given.
-
Structural optimization of thin elastic plates: the three dimensional approach
2010Co-Authors: Guy Bouchitté, Ilaria Fragalà, Pierre SeppecherAbstract:The natural way to find the most compliant design of an elastic plate, is to consider the three-dimensional elastic structures which minimize the work of the loading term, and pass to the limit when the thickness of the design region tends to zero. In this paper, we study the asymptotic of such Compliance Problem, imposing that the volume fraction remains fixed. No additional topological constraint is assumed on the admissible configurations. We determine the limit Problem in different equivalent formulations, and we provide a system of necessary and sufficient optimality conditions. These results were announced in [18]. Furthermore, we investigate the vanishing volume fraction limit, which turns out to be consistent with the results in [16, 17]. Finally, some explicit computation of optimal plates are given.
-
The optimal Compliance Problem for thin torsion rods: A 3D-1D analysis leading to Cheeger-type solutions
Comptes Rendus Mathematique, 2010Co-Authors: Guy Bouchitté, Ilaria Fragalà, Pierre SeppecherAbstract:Abstract We consider the variational Problem which consists in minimizing the Compliance of a prescribed amount of isotropic elastic material placed into a given design region when it is subjected to a given load. We perform the asymptotics of this Problem when the design region is a straight cylinder with infinitesimal cross section. The results presented in this Note concern the pure torsion regime and state the existence of optimal shapes for the limit Problem. When the filling ratio tends in turn to zero, these optimal shapes concentrate on the boundary of the Cheeger set of the section of the design region.
-
3D–2D analysis for the optimal elastic Compliance Problem
Comptes Rendus Mathematique, 2007Co-Authors: Guy Bouchitté, Ilaria Fragalà, Pierre SeppecherAbstract:Abstract We consider the variational Problems which consist in minimizing the Compliance of a prescribed amount of elastic material which is subject to a given load and is placed in a design region of infinitesimal height. We determine the limit Problem, and we provide necessary and sufficient optimality conditions. To cite this article: G. Bouchitte et al., C. R. Acad. Sci. Paris, Ser. I 345 (2007).
Guy Bouchitté - One of the best experts on this subject based on the ideXlab platform.
-
Structural Optimization of Thin Elastic Plates: The Three Dimensional Approach
Archive for Rational Mechanics and Analysis, 2011Co-Authors: Guy Bouchitté, Ilaria Fragalà, Pierre SeppecherAbstract:The natural way to find the most compliant design of an elastic plate is to consider the three-dimensional elastic structures which minimize the work of the loading term, and pass to the limit when the thickness of the design region tends to zero. In this paper, we study the asymptotics of such a Compliance Problem, imposing that the volume fraction remains fixed. No additional topological constraint is assumed on the admissible configurations. We determine the limit Problem in different equivalent formulations, and we provide a system of necessary and sufficient optimality conditions. These results were announced in Bouchitté et al. (C. R. Acad. Sci. Paris, Ser. I. 345:713–718, 2007). Furthermore, we investigate the vanishing volume fraction limit, which turns out to be consistent with the results in Bouchitté and Fragalà (Arch. Rat. Mech. Anal. 184:257–284, 2007; SIAM J. Control Optim. 46:1664–1682, 2007). Finally, some explicit computation of optimal plates are given.
-
Structural optimization of thin elastic plates: the three dimensional approach
2010Co-Authors: Guy Bouchitté, Ilaria Fragalà, Pierre SeppecherAbstract:The natural way to find the most compliant design of an elastic plate, is to consider the three-dimensional elastic structures which minimize the work of the loading term, and pass to the limit when the thickness of the design region tends to zero. In this paper, we study the asymptotic of such Compliance Problem, imposing that the volume fraction remains fixed. No additional topological constraint is assumed on the admissible configurations. We determine the limit Problem in different equivalent formulations, and we provide a system of necessary and sufficient optimality conditions. These results were announced in [18]. Furthermore, we investigate the vanishing volume fraction limit, which turns out to be consistent with the results in [16, 17]. Finally, some explicit computation of optimal plates are given.
-
The optimal Compliance Problem for thin torsion rods: A 3D-1D analysis leading to Cheeger-type solutions
Comptes Rendus Mathematique, 2010Co-Authors: Guy Bouchitté, Ilaria Fragalà, Pierre SeppecherAbstract:Abstract We consider the variational Problem which consists in minimizing the Compliance of a prescribed amount of isotropic elastic material placed into a given design region when it is subjected to a given load. We perform the asymptotics of this Problem when the design region is a straight cylinder with infinitesimal cross section. The results presented in this Note concern the pure torsion regime and state the existence of optimal shapes for the limit Problem. When the filling ratio tends in turn to zero, these optimal shapes concentrate on the boundary of the Cheeger set of the section of the design region.
-
3D–2D analysis for the optimal elastic Compliance Problem
Comptes Rendus Mathematique, 2007Co-Authors: Guy Bouchitté, Ilaria Fragalà, Pierre SeppecherAbstract:Abstract We consider the variational Problems which consist in minimizing the Compliance of a prescribed amount of elastic material which is subject to a given load and is placed in a design region of infinitesimal height. We determine the limit Problem, and we provide necessary and sufficient optimality conditions. To cite this article: G. Bouchitte et al., C. R. Acad. Sci. Paris, Ser. I 345 (2007).
Shinji Nishiwaki - One of the best experts on this subject based on the ideXlab platform.
-
Reliability-based topology optimization under shape uncertainty modeled in Eulerian description
Structural and Multidisciplinary Optimization, 2019Co-Authors: Yuki Sato, Kazuhiro Izui, Shinji Nishiwaki, Takayuki Yamada, Nozomu KogisoAbstract:This paper presents a reliability-based topology optimization method under geometrical uncertainties. First, we briefly introduce the concept of topology optimization. Then, we explain how shape uncertainty is modeled in Eulerian description, using an advection equation and a Karhunen-Loève expansion. Based on the shape uncertainty modeling, we formulate a reliability measure for the shape uncertainty, briefly introducing the inverse reliability method. Two optimization Problems, a minimum mean Compliance Problem and an optimum design Problem for a compliant mechanism, are then formulated using the proposed shape uncertainty modeling. The design sensitivity analysis for the reliability analysis and optimization procedure, performed using the adjoint variable method, is then explained. A two-level optimization algorithm is constructed next, in which the inner iteration is used for reliability analysis and the outer is used for updating design variables. Finally, three numerical examples are provided to demonstrate the validity and the utility of the proposed method.
-
heaviside projection based topology optimization by a pde filtered scalar function
Structural and Multidisciplinary Optimization, 2011Co-Authors: Atsushi Kawamoto, Tsuyoshi Nomura, Shintaro Yamasaki, Tadayoshi Matsumori, Tsuguo Kondoh, Shinji NishiwakiAbstract:This paper deals with topology optimization based on the Heaviside projection method using a scalar function as design variables. The scalar function is then regularized by a PDE based filter. Several image-processing based filtering techniques have so far been proposed for regularization or restricting the minimum length scale. They are conventionally applied to the design sensitivities rather than the design variables themselves. However, it causes discrepancies between the filtered sensitivities and the actual sensitivities that may confuse the optimization process and disturb the convergence. In this paper, we propose a Heaviside projection based topology optimization method with a scalar function that is filtered by a Helmholtz type partial differential equation. Therefore, the optimality can be strictly discussed in terms of the KKT condition. In order to demonstrate the effectiveness of the proposed method, a minimum Compliance Problem is solved.
-
a structural optimization method incorporating level set boundary expressions based on the concept of the phase field method
Journal of Environment and Engineering, 2011Co-Authors: Takayuki Yamada, Kazuhiro Izui, Shinji Nishiwaki, Masataka Yoshimura, Akihiro TakezawaAbstract:Topology optimization has been successfully used in many industries, especially those engaged in the design and manufacturing of mechanical devices, but numerical Problems are often encountered, such as grayscale representations of obtained composites. A type of structural optimization method using the level set theory for boundary expressions has been proposed, in which the outlines of target structures are implicitly represented using the level set function, and optimal configurations are obtained by updating this function based on the shape sensitivities. Level set-based methods typically have a drawback, however, in that topological changes that increase the number of holes in the material domain are not allowed. To overcome the above numerical and topological Problems, this paper proposes a new topology optimization method incorporating level set boundary expressions based on the concept of the phase field method, which we apply to a minimum mean Compliance Problem. First, a structural optimization Problem is formulated based on a boundary expression, using the level set function. Next, a time evolutionary equation for updating the level set function is formulated based on the concept of the phase field method, and the minimum mean Compliance Problem is formulated using a level set boundary expression. An optimization algorithm for the topology optimization incorporating the level set boundary expression based on the concept of the phase field method is then derived. Several examples are provided to confirm the usefulness of the proposed structural topology optimization method.
-
a level set based topology optimization method using the discretized signed distance function as the design variables
Structural and Multidisciplinary Optimization, 2010Co-Authors: Shintaro Yamasaki, Tsuyoshi Nomura, Atsushi Kawamoto, Kazuhiro Izui, Kazuo Sato, Shinji NishiwakiAbstract:This paper deals with a new topology optimization method based on the level set method. In the proposed method, the discretized signed distance function, a kind of level set function, is used as the design variables, and these are then updated using their sensitivities. The signed distance characteristic of the design variables are maintained by performing a re-initialization at every update during the iterated optimization procedure. In this paper, a minimum mean Compliance Problem and a compliant mechanism design Problem are formulated based on the level set method. In the formulations of these design Problems, a perimeter constraint is imposed to overcome the ill-posedness of the structural optimization Problem. The sensitivity analysis for the above structural optimization Problems is conducted based on the adjoint variable method. The augmented Lagrangian method is incorporated to deal with multiple constraints. Finally, several numerical examples that include multiple constraints are provided to confirm the validity of the method, and it is shown that appropriate optimal structures are obtained.
Guido Governatori - One of the best experts on this subject based on the ideXlab platform.
-
Are we done with business process Compliance: state of the art and challenges ahead
Knowledge and Information Systems, 2018Co-Authors: Mustafa Hashmi, Guido Governatori, Moe Thandar WynnAbstract:Literature on business process Compliance (BPC) has predominantly focused on the alignment of the regulatory rules with the design, verification and validation of business processes. Previously, surveys on BPC have been conducted with specific context in mind; however, the literature on BPC management research is largely sparse and does not accumulate a detailed understanding on existing literature and related issues faced by the domain. This survey provides a holistic view of the literature on existing BPC management approaches and categorises them based on different Compliance management strategies in the context of formulated research questions. A systematic literature approach is used where search terms pertaining keywords were used to identify literature related to the research questions from scholarly databases. From initially 183 papers, we selected 79 papers related to the themes of this survey published between 2000 and 2015. The survey results reveal that mostly Compliance management approaches centre around three distinct categories, namely design-time ( $$28\%$$ 28 % ), run-time ( $$32\%$$ 32 % ) and auditing ( $$10\%$$ 10 % ). Also, organisational and internal control-based Compliance management frameworks ( $$21\%$$ 21 % ) and hybrid approaches make ( $$9\%$$ 9 % ) of the surveyed approaches. Furthermore, open research challenges and gaps are identified and discussed with respect to the Compliance Problem.
-
Business Process Regulatory Compliance is Hard
IEEE Transactions on Services Computing, 2015Co-Authors: Silvano Colombo Tosatto, Guido Governatori, Pierre KelsenAbstract:Verifying whether a business process is compliant with a regulatory framework is a difficult task. In the present paper we prove the hardness of the business process regulatory Compliance Problem by taking into account a sub-Problem of the general Problem. This limited Problem allows to verify only the Compliance of structured processes with respect to a regulatory framework composed of a set of conditional obligations including a deadline. Experimental evidence from existing studies shows that Compliance is a difficult task. In this paper, despite considering a sub-Problem of the general Problem, we provide some theoretical evidence of the difficulty of the task. In particular we show that the source of the complexity lies in the core language of verifying conditional obligations with a deadline. We prove that for this simplified case verifying partial Compliance belongs to the class of NP -complete Problems, and verifying full Compliance belongs to the class of co NP -complete Problems. Thus by proving the difficulty of a simplified Compliance Problem we prove that the general Problem of verifying business process regulatory Compliance is hard.
-
Algorithms for tractable Compliance Problems
Frontiers of Computer Science, 2014Co-Authors: Silvano Colombo Tosatto, Guido Governatori, Pierre Kelsen, Marwane El Kharbili, Leendert Van Der TorreAbstract:In general the Problem of verifying whether a structured business process is compliant with a given set of regulations is NP-hard. The present paper focuses on identifying a tractable subset of this Problem, namely verifying whether a structured business process is compliant with a single global obligation. Global obligations are those whose validity spans for the entire execution of a business process. We identify two types of obligations: achievement and maintenance. In the present paper we firstly define an abstract framework capable to model the Problem and secondly we define procedures and algorithms to deal with the Compliance Problem of checking the Compliance of a structured business process with respect to a single global obligation. We show that the algorithms proposed in the paper run in polynomial time.
-
EDOC Workshops - Towards an Abstract Framework for Compliance
2013 17th IEEE International Enterprise Distributed Object Computing Conference Workshops, 2013Co-Authors: Silvano Colombo Tosatto, Guido Governatori, Pierre KelsenAbstract:The present paper aims at providing an abstract framework to define the regulatory Compliance Problem. In particular we show how the framework can be used to solve the Problem of deciding whether a structured process is compliant with a single regulation, which is composed of a primary obligation and a chain of compensations.
-
ICST Workshops - Algorithms for Basic Compliance Problems
2013 IEEE Sixth International Conference on Software Testing Verification and Validation Workshops, 2013Co-Authors: Silvano Colombo Tosatto, Guido Governatori, Pierre Kelsen, Marwane El Kharbili, Leendert Van Der TorreAbstract:The present paper focuses on the Problems of verifying Compliance for global achievement and maintenance obligations. We first introduce the elements needed to identify and study Compliance to these two classes of obligations in processes. Additionally, we define procedures and algorithms to efficiently deal with the identified Compliance Problem. We finally show that both algorithms proposed in the paper belong to the complexity class P.
Ilaria Fragalà - One of the best experts on this subject based on the ideXlab platform.
-
Structural Optimization of Thin Elastic Plates: The Three Dimensional Approach
Archive for Rational Mechanics and Analysis, 2011Co-Authors: Guy Bouchitté, Ilaria Fragalà, Pierre SeppecherAbstract:The natural way to find the most compliant design of an elastic plate is to consider the three-dimensional elastic structures which minimize the work of the loading term, and pass to the limit when the thickness of the design region tends to zero. In this paper, we study the asymptotics of such a Compliance Problem, imposing that the volume fraction remains fixed. No additional topological constraint is assumed on the admissible configurations. We determine the limit Problem in different equivalent formulations, and we provide a system of necessary and sufficient optimality conditions. These results were announced in Bouchitté et al. (C. R. Acad. Sci. Paris, Ser. I. 345:713–718, 2007). Furthermore, we investigate the vanishing volume fraction limit, which turns out to be consistent with the results in Bouchitté and Fragalà (Arch. Rat. Mech. Anal. 184:257–284, 2007; SIAM J. Control Optim. 46:1664–1682, 2007). Finally, some explicit computation of optimal plates are given.
-
Structural optimization of thin elastic plates: the three dimensional approach
2010Co-Authors: Guy Bouchitté, Ilaria Fragalà, Pierre SeppecherAbstract:The natural way to find the most compliant design of an elastic plate, is to consider the three-dimensional elastic structures which minimize the work of the loading term, and pass to the limit when the thickness of the design region tends to zero. In this paper, we study the asymptotic of such Compliance Problem, imposing that the volume fraction remains fixed. No additional topological constraint is assumed on the admissible configurations. We determine the limit Problem in different equivalent formulations, and we provide a system of necessary and sufficient optimality conditions. These results were announced in [18]. Furthermore, we investigate the vanishing volume fraction limit, which turns out to be consistent with the results in [16, 17]. Finally, some explicit computation of optimal plates are given.
-
The optimal Compliance Problem for thin torsion rods: A 3D-1D analysis leading to Cheeger-type solutions
Comptes Rendus Mathematique, 2010Co-Authors: Guy Bouchitté, Ilaria Fragalà, Pierre SeppecherAbstract:Abstract We consider the variational Problem which consists in minimizing the Compliance of a prescribed amount of isotropic elastic material placed into a given design region when it is subjected to a given load. We perform the asymptotics of this Problem when the design region is a straight cylinder with infinitesimal cross section. The results presented in this Note concern the pure torsion regime and state the existence of optimal shapes for the limit Problem. When the filling ratio tends in turn to zero, these optimal shapes concentrate on the boundary of the Cheeger set of the section of the design region.
-
3D–2D analysis for the optimal elastic Compliance Problem
Comptes Rendus Mathematique, 2007Co-Authors: Guy Bouchitté, Ilaria Fragalà, Pierre SeppecherAbstract:Abstract We consider the variational Problems which consist in minimizing the Compliance of a prescribed amount of elastic material which is subject to a given load and is placed in a design region of infinitesimal height. We determine the limit Problem, and we provide necessary and sufficient optimality conditions. To cite this article: G. Bouchitte et al., C. R. Acad. Sci. Paris, Ser. I 345 (2007).