Articles de revista
http://hdl.handle.net/2117/6145
20170821T06:55:00Z

Catalogue of vibration reduction index formulas for heavy junctions based on numerical simulations
http://hdl.handle.net/2117/106840
Catalogue of vibration reduction index formulas for heavy junctions based on numerical simulations
PobletPuig, Jordi; GuigouCarter, Catherine
The vibration reduction index (Kij) is a key parameter in the prediction of flanking transmissions according to the EN12354 standard. Formulas for the evaluation of Kij in L, T and X junctions that depend on the mass ratio are available in the Annex E. Junctions of straight elements with different thickness or thin elastic layers are also included. However, other junction types that are important for building industry are not considered: Hshaped junctions, L or T junctions not forming a right angle, asymmetrical Tjunctions , Xjunctions where only one of the parts is different (thickness or material) from the other two/three. In the current research, expressions for these noncovered junctions are provided. They are obtained by means of numerical simulations based on the spectral finite element method. Kij is predicted for a large population of junctions, considering usual thicknesses and heavy material combinations (no lightweight frame systems have been considered). Statistical analysis is carried out to obtain relatively simple formulae that could be used in acoustic design projects without the need for timeconsuming computations with finite element software.
© (2017) S. Hirzel Verlag/European Acoustics Association.
The definitive publisherauthenticated version is available online at http://www.ingentaconnect.com/contentone/dav/aaua/2017/00000103/00000004/art00011 and http//dx.doi.org/10.3813/AAA.919091.
Readers must contact the publisher for reprint or permission to use the material in any form.
20170725T14:29:02Z
PobletPuig, Jordi
GuigouCarter, Catherine
The vibration reduction index (Kij) is a key parameter in the prediction of flanking transmissions according to the EN12354 standard. Formulas for the evaluation of Kij in L, T and X junctions that depend on the mass ratio are available in the Annex E. Junctions of straight elements with different thickness or thin elastic layers are also included. However, other junction types that are important for building industry are not considered: Hshaped junctions, L or T junctions not forming a right angle, asymmetrical Tjunctions , Xjunctions where only one of the parts is different (thickness or material) from the other two/three. In the current research, expressions for these noncovered junctions are provided. They are obtained by means of numerical simulations based on the spectral finite element method. Kij is predicted for a large population of junctions, considering usual thicknesses and heavy material combinations (no lightweight frame systems have been considered). Statistical analysis is carried out to obtain relatively simple formulae that could be used in acoustic design projects without the need for timeconsuming computations with finite element software.

Coupled mantle dripping and lateral dragging controlling the lithosphere structure of the NWMoroccan margin and the Atlas Mountains: A numerical experiment
http://hdl.handle.net/2117/105402
Coupled mantle dripping and lateral dragging controlling the lithosphere structure of the NWMoroccan margin and the Atlas Mountains: A numerical experiment
Zlotnik, Sergio; JiménezMunt, Ivone; Fernández Gómez, Manel
Recent studies integrating gravity, geoid, surface heat flow, elevation and seismic data indicate a prominent lithospheric mantle thickening beneath the NWMoroccan margin (LAB >200 kmdepth) followed by thinning beneath the Atlas Domain (LAB about 80 kmdepth). Such unusual configuration has been explained by the combination of mantle underthrusting due to oblique AfricaEurasia convergence together with viscous dripping fed by asymmetric lateral mantle dragging, requiring a strong crustmantle decoupling. In the present work we examine the physical conditions under which the proposed asymmetric mantle drip and drag mechanism can reproduce this lithospheric configuration. We also analyse the influence of varying the kinematic boundary conditions as well as the mantle viscosity and the initial lithosphere geometry. Results indicate that the proposed dripdrag mechanism is dynamically feasible and only requires a lateral variation of the lithospheric strength. The further evolution of the gravitational instability can become either in convective removal of the lithospheric mantle, mantle delamination, or subduction initiation. The model reproduces the main trends of the presentday lithospheric geometry across the NWMoroccan margin and the Atlas Mountains, the characteristic time of the observed vertical movements, the amplitude and rates of uplift in the Atlas Mountains and offers an explanation to the Miocene to Pliocene volcanism. An abnormal constant tectonic subsidence rate in the margin is predicted. (C) 2013 Elsevier B.V. All rights reserved.
20170614T10:13:23Z
Zlotnik, Sergio
JiménezMunt, Ivone
Fernández Gómez, Manel
Recent studies integrating gravity, geoid, surface heat flow, elevation and seismic data indicate a prominent lithospheric mantle thickening beneath the NWMoroccan margin (LAB >200 kmdepth) followed by thinning beneath the Atlas Domain (LAB about 80 kmdepth). Such unusual configuration has been explained by the combination of mantle underthrusting due to oblique AfricaEurasia convergence together with viscous dripping fed by asymmetric lateral mantle dragging, requiring a strong crustmantle decoupling. In the present work we examine the physical conditions under which the proposed asymmetric mantle drip and drag mechanism can reproduce this lithospheric configuration. We also analyse the influence of varying the kinematic boundary conditions as well as the mantle viscosity and the initial lithosphere geometry. Results indicate that the proposed dripdrag mechanism is dynamically feasible and only requires a lateral variation of the lithospheric strength. The further evolution of the gravitational instability can become either in convective removal of the lithospheric mantle, mantle delamination, or subduction initiation. The model reproduces the main trends of the presentday lithospheric geometry across the NWMoroccan margin and the Atlas Mountains, the characteristic time of the observed vertical movements, the amplitude and rates of uplift in the Atlas Mountains and offers an explanation to the Miocene to Pliocene volcanism. An abnormal constant tectonic subsidence rate in the margin is predicted. (C) 2013 Elsevier B.V. All rights reserved.

Flight and passenger delay assignment optimization strategies
http://hdl.handle.net/2117/105306
Flight and passenger delay assignment optimization strategies
Villardi de Montlaur, Adeline de; Delgado Muñoz, Luis
This paper compares different optimization strategies for the minimization of flight and passenger delays at two levels: pretactical, with onground delay at origin, and tactical, with airborne delay close to the destination airport. The optimization model is based on the ground holding problem and uses various cost functions. The scenario considered takes place in a busy European airport and includes realistic values of traffic. A passenger assignment with connections at the hub is modeled. Statistical models are used for passenger and connecting passenger allocation, minimum time required for turnaround and tactical noise; whereas uncertainty is also introduced in the model for tactical noise. Performance of the various optimization processes is presented and compared to ration by schedule results.
20170609T15:10:25Z
Villardi de Montlaur, Adeline de
Delgado Muñoz, Luis
This paper compares different optimization strategies for the minimization of flight and passenger delays at two levels: pretactical, with onground delay at origin, and tactical, with airborne delay close to the destination airport. The optimization model is based on the ground holding problem and uses various cost functions. The scenario considered takes place in a busy European airport and includes realistic values of traffic. A passenger assignment with connections at the hub is modeled. Statistical models are used for passenger and connecting passenger allocation, minimum time required for turnaround and tactical noise; whereas uncertainty is also introduced in the model for tactical noise. Performance of the various optimization processes is presented and compared to ration by schedule results.

Use of wiris quizzes in an online calculus course
http://hdl.handle.net/2117/105260
Use of wiris quizzes in an online calculus course
Calm, Remei; Masià, Ramon; Olivé, Carme; Parés Mariné, Núria; Pozo Montero, Francesc; Ripoll, Jordi; Sancho Vinuesa, Teresa
Calculus courses often present a large number of difficulties to undergraduate students of scientific studies, especially in engineering degrees. These difficulties are sometimes related to teaching and assessment strategies. In this paper, a teaching innovation experience is presented within the framework of the Universitat Oberta de Catalunya. This teaching experience is focused on a continuous assessment through a systematic use of the socalled WIRIS quizzes. Academic outcomes are very positive from both quantitative and qualitative viewpoints.
20170609T06:29:14Z
Calm, Remei
Masià, Ramon
Olivé, Carme
Parés Mariné, Núria
Pozo Montero, Francesc
Ripoll, Jordi
Sancho Vinuesa, Teresa
Calculus courses often present a large number of difficulties to undergraduate students of scientific studies, especially in engineering degrees. These difficulties are sometimes related to teaching and assessment strategies. In this paper, a teaching innovation experience is presented within the framework of the Universitat Oberta de Catalunya. This teaching experience is focused on a continuous assessment through a systematic use of the socalled WIRIS quizzes. Academic outcomes are very positive from both quantitative and qualitative viewpoints.

Simulating squeeze flows in multiaxial laminates: towards fully 3D mixed formulations
http://hdl.handle.net/2117/104744
Simulating squeeze flows in multiaxial laminates: towards fully 3D mixed formulations
Ibáñez, Rubén; AbissetChavanne, Emmanuelle; Chinesta, Francisco; Huerta, Antonio
Thermoplastic composites are widely considered in structural parts. In this paper attention is paid to squeeze flow of continuous fiber laminates. In the case of unidirectional prepregs, the ply constitutive equation is modeled as a transversally isotropic fluid, that must satisfy both the fiber inextensibility as well as the fluid incompressibility. When laminate is squeezed the flow kinematics exhibits a complex dependency along the laminate thickness requiring a detailed velocity description through the thickness. In a former work the solution making use of an inplaneoutofplane separated representation within the PGD – Poper Generalized Decomposition – framework was successfully accomplished when both kinematic constraints (inextensibility and incompressibility) were introduced using a penalty formulation for circumventing the LBB constraints. However, such a formulation makes difficult the calculation on fiber tractions and compression forces, the last required in rheological characterizations. In this paper the former penalty formulation is substituted by a mixed formulation that makes use of two Lagrange multipliers, while addressing the LBB stability conditions within the separated representation framework, questions never until now addressed.
The final publication is available at Springer via http://dx.doi.org/10.1007/s1228901613094
20170523T09:30:30Z
Ibáñez, Rubén
AbissetChavanne, Emmanuelle
Chinesta, Francisco
Huerta, Antonio
Thermoplastic composites are widely considered in structural parts. In this paper attention is paid to squeeze flow of continuous fiber laminates. In the case of unidirectional prepregs, the ply constitutive equation is modeled as a transversally isotropic fluid, that must satisfy both the fiber inextensibility as well as the fluid incompressibility. When laminate is squeezed the flow kinematics exhibits a complex dependency along the laminate thickness requiring a detailed velocity description through the thickness. In a former work the solution making use of an inplaneoutofplane separated representation within the PGD – Poper Generalized Decomposition – framework was successfully accomplished when both kinematic constraints (inextensibility and incompressibility) were introduced using a penalty formulation for circumventing the LBB constraints. However, such a formulation makes difficult the calculation on fiber tractions and compression forces, the last required in rheological characterizations. In this paper the former penalty formulation is substituted by a mixed formulation that makes use of two Lagrange multipliers, while addressing the LBB stability conditions within the separated representation framework, questions never until now addressed.

Algebraic and parametric solvers for the power flow problem: towards realtime and accuracyguaranteed simulation of electric systems
http://hdl.handle.net/2117/104740
Algebraic and parametric solvers for the power flow problem: towards realtime and accuracyguaranteed simulation of electric systems
García Blanco, Raquel; Díez, Pedro; Borzacchiello, Domenico; Chinesta, Francisco
The power flow model performs the analysis of electric distribution and transmission systems. With this statement at hand, in this work we present a summary of those solvers for the power flow equations, in both algebraic and parametric version. The application of the Alternating Search Direction method to the power flow problem is also detailed. This results in a family of iterative solvers that combined with Proper Generalized Decomposition technique allows to solve the parametric version of the equations. Once the solution is computed using this strategy, analyzing the network state or solving optimization problems, with inclusion of generation in realtime, becomes a straightforward procedure since the parametric solution is available. Complementing this approach, an error strategy is implemented at each step of the iterative solver. Thus, error indicators are used as an stopping criteria controlling the accuracy of the approximation during the construction process. The application of these methods to the model IEEE 57bus network is taken as a numerical illustration.
The final publication is available at Springer via http://dx.doi.org/10.1007/s1183101792236
20170523T08:58:21Z
García Blanco, Raquel
Díez, Pedro
Borzacchiello, Domenico
Chinesta, Francisco
The power flow model performs the analysis of electric distribution and transmission systems. With this statement at hand, in this work we present a summary of those solvers for the power flow equations, in both algebraic and parametric version. The application of the Alternating Search Direction method to the power flow problem is also detailed. This results in a family of iterative solvers that combined with Proper Generalized Decomposition technique allows to solve the parametric version of the equations. Once the solution is computed using this strategy, analyzing the network state or solving optimization problems, with inclusion of generation in realtime, becomes a straightforward procedure since the parametric solution is available. Complementing this approach, an error strategy is implemented at each step of the iterative solver. Thus, error indicators are used as an stopping criteria controlling the accuracy of the approximation during the construction process. The application of these methods to the model IEEE 57bus network is taken as a numerical illustration.

Enhanced goaloriented error assessment and computational strategies in adaptive reduced basis solver for stochastic problems
http://hdl.handle.net/2117/104348
Enhanced goaloriented error assessment and computational strategies in adaptive reduced basis solver for stochastic problems
Serafin, Kevin; Magnain, Benoît; Florentin, Eric; Parés Mariné, Núria; Díez, Pedro
This work focuses on providing accurate lowcost approximations of stochastic ¿nite elements simulations in the framework of linear elasticity. In a previous work, an adaptive strategy was introduced as an improved MonteCarlo method for multidimensional large stochastic problems. We provide here a complete analysis of the method including a new enhanced goaloriented error estimator and estimates of CPU (computational processing unit) cost gain. Technical insights of these two topics are presented in details, and numerical examples show the interest of these new developments.
20170512T08:34:35Z
Serafin, Kevin
Magnain, Benoît
Florentin, Eric
Parés Mariné, Núria
Díez, Pedro
This work focuses on providing accurate lowcost approximations of stochastic ¿nite elements simulations in the framework of linear elasticity. In a previous work, an adaptive strategy was introduced as an improved MonteCarlo method for multidimensional large stochastic problems. We provide here a complete analysis of the method including a new enhanced goaloriented error estimator and estimates of CPU (computational processing unit) cost gain. Technical insights of these two topics are presented in details, and numerical examples show the interest of these new developments.

Generation of curved highorder meshes with optimal quality and geometric accuracy
http://hdl.handle.net/2117/103875
Generation of curved highorder meshes with optimal quality and geometric accuracy
Ruiz Gironés, Eloi; Sarrate Ramos, Josep; Roca Navarro, Xevi
We present a novel methodology to generate curved highorder meshes featuring optimal mesh quality and geometric accuracy. The proposed technique combines a distortion measure and a geometric L2disparity measure into a single objective function. While the element distortion term takes into account the mesh quality, the L2disparity term takes into account the geometric error introduced by the mesh approximation to the target geometry. The proposed technique has several advantages. First, we are not restricted to interpolative meshes and therefore, the resulting mesh approximates the target domain in a noninterpolative way, further increasing the geometric accuracy. Second, we are able to generate a series of meshes that converge to the actual geometry with expected rate while obtaining highquality elements. Third, we show that the proposed technique is robust enough to handle realcase geometries that contain gaps between adjacent entities.
20170502T05:54:53Z
Ruiz Gironés, Eloi
Sarrate Ramos, Josep
Roca Navarro, Xevi
We present a novel methodology to generate curved highorder meshes featuring optimal mesh quality and geometric accuracy. The proposed technique combines a distortion measure and a geometric L2disparity measure into a single objective function. While the element distortion term takes into account the mesh quality, the L2disparity term takes into account the geometric error introduced by the mesh approximation to the target geometry. The proposed technique has several advantages. First, we are not restricted to interpolative meshes and therefore, the resulting mesh approximates the target domain in a noninterpolative way, further increasing the geometric accuracy. Second, we are able to generate a series of meshes that converge to the actual geometry with expected rate while obtaining highquality elements. Third, we show that the proposed technique is robust enough to handle realcase geometries that contain gaps between adjacent entities.

Bulging brains
http://hdl.handle.net/2117/103778
Bulging brains
Weickenmeie, J.; Sáez Viñas, Pablo; Butler, C. A.; Young, P.G.; Gorily, A.; Kuhl, Ellen
Brain swelling is a serious condition associated with an accumulation of fluid inside the brain caused by trauma, stroke, infection, or tumors. It increases the pressure inside the skull and reduces blood and oxygen supply. To relieve the intracranial pressure, neurosurgeons remove part of the skull and allow the swollen brain to bulge outward, a procedure that is widely known as decompressive craniectomy. Decompressive craniectomy has been preformed for more than a century; yet, its e¿ects on the swollen brain remain poorly understood. Here we characterize the deformation, strain, and stretch in bulging brains using the nonlinear field theories of mechanics. Our study shows that even small swelling volumes of 28 and 56ml induce maximum principal strains in excess of 30%. For radially outwardpointing axons, we observed maximal normal stretches of 1.3 deep inside the bulge and maximal shear stretches of 1.3 around the craniectomy edge. While the stretch magnitude varies with opening site and swelling site, our study suggests that the locations of maximum stretch are universally shared amongst all bulging brains. Our model can inform neurosurgeons and rationalize the shape and position of the skull opening, with the overall goal to reduce brain damage and improve the structural and functional outcomes of decompressive craniectomy.
The final publication is available at Springer via http://dx.doi.org/10.1007/s1065901696061
20170427T11:28:59Z
Weickenmeie, J.
Sáez Viñas, Pablo
Butler, C. A.
Young, P.G.
Gorily, A.
Kuhl, Ellen
Brain swelling is a serious condition associated with an accumulation of fluid inside the brain caused by trauma, stroke, infection, or tumors. It increases the pressure inside the skull and reduces blood and oxygen supply. To relieve the intracranial pressure, neurosurgeons remove part of the skull and allow the swollen brain to bulge outward, a procedure that is widely known as decompressive craniectomy. Decompressive craniectomy has been preformed for more than a century; yet, its e¿ects on the swollen brain remain poorly understood. Here we characterize the deformation, strain, and stretch in bulging brains using the nonlinear field theories of mechanics. Our study shows that even small swelling volumes of 28 and 56ml induce maximum principal strains in excess of 30%. For radially outwardpointing axons, we observed maximal normal stretches of 1.3 deep inside the bulge and maximal shear stretches of 1.3 around the craniectomy edge. While the stretch magnitude varies with opening site and swelling site, our study suggests that the locations of maximum stretch are universally shared amongst all bulging brains. Our model can inform neurosurgeons and rationalize the shape and position of the skull opening, with the overall goal to reduce brain damage and improve the structural and functional outcomes of decompressive craniectomy.

Hierarchical microadaptation of biological structures by mechanical stimuli
http://hdl.handle.net/2117/103710
Hierarchical microadaptation of biological structures by mechanical stimuli
Sáez Viñas, Pablo; Pena, Estefanía; Doblaré, Manuel; Martínez, Miguel Ángel
Remodeling and other evolving processes such as growth or morphogenesis are key factors in the evolution of biological tissue in response to both external and internal epigenetic stimuli. Based on the description of these processes provided by Taber, 1995 and Humphrey et al., 2002 for three important adaptation processes, remodeling, morphogenesis and growth (positive and negative), we shall consider the latter as the increase/decrease of mass via the increase/decrease of the number or size of cells, leading to a change in the volume of the organ. The work of Rodriguez et al. (1994) used the concept of natural configuration previously introduced by Skalak et al. (1982) to formulate volumetric growth. Later, Humphrey et al. (2002) proposed a constrainedmixture theory where changes in the density and mass of different constituents were taken into account. Many other works about biological growth have been presented in recent years, see e.g. Imatani and Maugin, 2002, Garikipati et al., 2004, Gleason and Humphrey, 2004, Menzel, 2004, Amar et al., 2005, Ganghoffer et al., 2005, Ateshian, 2007, Goriely et al., 2007, Kuhl et al., 2007, Ganghoffer, 2010a, Ganghoffer, 2010b and Goktepe et al., 2010. Morphogenesis is associated to changes in the structure shape (Taber, 1995 and Taber, 2009) while remodeling denotes changes in the tissue microstructure via the reorganization of the existing constituents or the synthesis of new ones with negligible volume change. All these processes involve changes in material properties. Although remodeling and growth can, and usually do, occur simultaneously, there are some cases where these processes develop in a decoupled way. For example, Stopak and Harris (1982) reported some experimental results showing remodeling driven by fibroblasts, with no volume growth. We will assume this scenario in this contribution, focusing exclusively on remodeling processes and on the reorientation of fibered biological structures.
It is well known that biological tissue remodels itself when driven by a given stimulus, e.g. mechanical loads such as an increase in blood pressure, or changes in the chemical environment that control the signaling processes and the overall evolution of the tissue. Biological remodeling can occur in any kind of biological tissue. In particular, the study of collagen as the most important substance to be remodeled, in all its types (preferentially
20170425T11:52:01Z
Sáez Viñas, Pablo
Pena, Estefanía
Doblaré, Manuel
Martínez, Miguel Ángel
Remodeling and other evolving processes such as growth or morphogenesis are key factors in the evolution of biological tissue in response to both external and internal epigenetic stimuli. Based on the description of these processes provided by Taber, 1995 and Humphrey et al., 2002 for three important adaptation processes, remodeling, morphogenesis and growth (positive and negative), we shall consider the latter as the increase/decrease of mass via the increase/decrease of the number or size of cells, leading to a change in the volume of the organ. The work of Rodriguez et al. (1994) used the concept of natural configuration previously introduced by Skalak et al. (1982) to formulate volumetric growth. Later, Humphrey et al. (2002) proposed a constrainedmixture theory where changes in the density and mass of different constituents were taken into account. Many other works about biological growth have been presented in recent years, see e.g. Imatani and Maugin, 2002, Garikipati et al., 2004, Gleason and Humphrey, 2004, Menzel, 2004, Amar et al., 2005, Ganghoffer et al., 2005, Ateshian, 2007, Goriely et al., 2007, Kuhl et al., 2007, Ganghoffer, 2010a, Ganghoffer, 2010b and Goktepe et al., 2010. Morphogenesis is associated to changes in the structure shape (Taber, 1995 and Taber, 2009) while remodeling denotes changes in the tissue microstructure via the reorganization of the existing constituents or the synthesis of new ones with negligible volume change. All these processes involve changes in material properties. Although remodeling and growth can, and usually do, occur simultaneously, there are some cases where these processes develop in a decoupled way. For example, Stopak and Harris (1982) reported some experimental results showing remodeling driven by fibroblasts, with no volume growth. We will assume this scenario in this contribution, focusing exclusively on remodeling processes and on the reorientation of fibered biological structures.
It is well known that biological tissue remodels itself when driven by a given stimulus, e.g. mechanical loads such as an increase in blood pressure, or changes in the chemical environment that control the signaling processes and the overall evolution of the tissue. Biological remodeling can occur in any kind of biological tissue. In particular, the study of collagen as the most important substance to be remodeled, in all its types (preferentially