Alexis Duarte - Academia.edu (original) (raw)
Papers by Alexis Duarte
High school students with Autism Spectrum Disorder demonstrate behaviors that inhibit reading com... more High school students with Autism Spectrum Disorder demonstrate behaviors that inhibit reading comprehension. This is due to atypical social mannerisms, lack of attention during instruction, and challenges staying on task. The purpose of this study is to explore the effects of literature circles during English class on reading comprehension. Statement of the Problem Students identified as having Autism Spectrum Disorder (ASD) present distinct behaviors that may hinder their success in an inclusive classroom. These behaviors include challenges during social interactions, lack of verbal communication during class, and difficulty with peer relationships (Good &Williams, 2007). Lack of engagement results in lack of attentive focus on academics. Challenges with peer collaboration impact their learning by limiting the amount of time they are actively engaged in the social aspects of learning. When these difficulties are combined, they impede students' academic success in the area of reading comprehension. According to Williamson, Carnhan, and Jacobs, (2012) the essence of reading is comprehension and this involves an interaction between the reader and the text. A vast number of high-functioning students with autism display impaired reading comprehension. According to O'Conner (2004) both decoding and reading comprehension levels are displayed on a continuum of performance, however reading comprehension falls well below other skills assessed. A key component to analytical reading is the ability to integrate information; students identified with ASD have difficulties with this abstract skill (O'Conner, 2004). Nation, Clarke, Wright, and Williams (2006) note that even amongst the fluent readers, comprehension scores are low.
The design of large parts of an airframe is driven by post buckling stability requirements. The a... more The design of large parts of an airframe is driven by post buckling stability requirements. The aim of the present work is to compare stability predictions obtained both by analytical and numerical methods. A study on the sensitivity of this method to material law has also been conducted. This way, the extent to which the precise shape of an high performance aluminium alloy stress / strain curve has an impact on stability results has been evaluated. Compression studies lead to acceptable differences between methods. The trend is however depending on the model : numerical calculations predict lower critical loads as well as upper ones. The field of improvement is undoubtedly modelling methods such as the introduction of a perturbation in the mesh and boundary conditions. More work is needed to better understand these differences. The study of the influence of the material also shows differences between both methods. Little changes are found when using detailed material model with ana...
The design of large parts of an airframe is driven by post buckling stability requirements. The a... more The design of large parts of an airframe is driven by post buckling stability requirements. The aim of the present work is to compare stability predictions obtained both by analytical and numerical methods. A study on the sensitivity of this method to material law has also been conducted. This way, the extent to which the precise shape of an high performance aluminium alloy stress / strain curve has an impact on stability results has been evaluated. Compression studies lead to acceptable differences between methods. The trend is however depending on the model : numeric al calculations predict lower critical loads as well as upper ones. The field of improvement is undoubtedly modelling methods such as the introduction of a perturbation in the mesh and boundary conditions. More work is needed to better understand these differences. The study of the influence of the material also shows differences between both methods. Little changes are found when using detailed material model with an...
43rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2002
The design of large parts of the airframe is driven by compression stability requirements. This s... more The design of large parts of the airframe is driven by compression stability requirements. This stability is generally evaluated using a Ramberg-Osgood (R-O) model of the material. The objective of the present work is to evaluate to what extent the precise shape of the stress-strain curve determines the outcome of the stability analysis. R-O-based material models with nc fitted for various ranges of plastic strain were compared to data measured both in the micro-plastic strain domain (between 0 and 0.2% strain) and conventional stress-strain data (measured between roughly 0.2 and 8%) for an AA7xxx alloy. It was observed that R-O-based models are not capable of representing all of the measured data accurately: models fitted for larger ranges of strain (e.g. 0.2 – 1%) represented the stress-strain data measured in the micro-plastic domain poorly, and vice-versa. It was verified however, that when using the material models to compute critical stresses of post-buckling designs through analytical-empirical Euler-Engesser calculations, little improvement in precision over current generally accepted practice is possible. On the other hand, detailed comparisons of post-buckling stiffened panel stability with finite element analyses (FEA) did demonstrate room for improvement of the accuracy of the analysis by using a different stress-strain fit. This was concluded to be attributable to a more accurate representation of local phenomena: The analytical-empirical methods used model the buckling of the stiffener + effective plating as if it were the collapse of an idealized column. Strains are averaged over the entire section and therefore remain small. The buckling stress is determined by the tangent modulus at this small plastic strain. The higher the strain hardening as modeled in the R-O representation, the higher the tangent modulus for small strains and therefore the higher the predicted critical stress. Elastic-plastic geometrically non-linear FEA, on the contrary, is not limited to simulating a column. All deformations, however local, are taken into account. Also, manufacturing imperfections can be simulated. For the panel configuration and perturbation practice used for these studies, the simulations lead to locally high plastic strains. Trend analysis indicated that without the correct material models, different from the ones that are used conventionally, this may lead to non-negligible imprecision in the predicted performance of a stiffened panel when using FEA.
Volume 2: 28th Design Automation Conference, 2002
Designing a family of product variants that share some components usually entails a performance l... more Designing a family of product variants that share some components usually entails a performance loss relative to the individually optimized variants due to the commonality constraints. Choosing components for sharing may depend on what performance losses can be tolerated. This article presents a methodology for making commonality decisions while controlling individual performance losses. Previous work focused on evaluating individual performance losses due to pre-specified sharing. Trade-offs were identified for different platforms (i.e., the sets of components shared among products) by means of Pareto sets. In the present work an optimal design problem is formulated to choose product components to be shared without exceeding a user-specified performance loss tolerance. This enables the designer to control trade-offs and obtain optimal product family designs for different levels of performance losses in an attempt to maximize commonality. A family of automotive side frames is used t...
Structural and Multidisciplinary Optimization, 2004
Journal of Mechanical Design, 2005
Designing a family of product variants that share some components usually requires a compromise i... more Designing a family of product variants that share some components usually requires a compromise in performance relative to the individually optimized variants due to the commonality constraints. Choosing components for sharing may depend on what performance losses can be tolerated. In this article an optimal design problem is formulated to choose product components to be shared without exceeding user-specified bounds on performance. This enables the designer to control tradeoffs and obtain optimal product family designs for maximizing commonality at different levels of acceptable performance. A family of automotive body side frames is used to demonstrate the approach.
Archivos De Criminologia Criminalistica Y Seguridad Privada, 2012
High school students with Autism Spectrum Disorder demonstrate behaviors that inhibit reading com... more High school students with Autism Spectrum Disorder demonstrate behaviors that inhibit reading comprehension. This is due to atypical social mannerisms, lack of attention during instruction, and challenges staying on task. The purpose of this study is to explore the effects of literature circles during English class on reading comprehension. Statement of the Problem Students identified as having Autism Spectrum Disorder (ASD) present distinct behaviors that may hinder their success in an inclusive classroom. These behaviors include challenges during social interactions, lack of verbal communication during class, and difficulty with peer relationships (Good &Williams, 2007). Lack of engagement results in lack of attentive focus on academics. Challenges with peer collaboration impact their learning by limiting the amount of time they are actively engaged in the social aspects of learning. When these difficulties are combined, they impede students' academic success in the area of reading comprehension. According to Williamson, Carnhan, and Jacobs, (2012) the essence of reading is comprehension and this involves an interaction between the reader and the text. A vast number of high-functioning students with autism display impaired reading comprehension. According to O'Conner (2004) both decoding and reading comprehension levels are displayed on a continuum of performance, however reading comprehension falls well below other skills assessed. A key component to analytical reading is the ability to integrate information; students identified with ASD have difficulties with this abstract skill (O'Conner, 2004). Nation, Clarke, Wright, and Williams (2006) note that even amongst the fluent readers, comprehension scores are low.
The design of large parts of an airframe is driven by post buckling stability requirements. The a... more The design of large parts of an airframe is driven by post buckling stability requirements. The aim of the present work is to compare stability predictions obtained both by analytical and numerical methods. A study on the sensitivity of this method to material law has also been conducted. This way, the extent to which the precise shape of an high performance aluminium alloy stress / strain curve has an impact on stability results has been evaluated. Compression studies lead to acceptable differences between methods. The trend is however depending on the model : numerical calculations predict lower critical loads as well as upper ones. The field of improvement is undoubtedly modelling methods such as the introduction of a perturbation in the mesh and boundary conditions. More work is needed to better understand these differences. The study of the influence of the material also shows differences between both methods. Little changes are found when using detailed material model with ana...
The design of large parts of an airframe is driven by post buckling stability requirements. The a... more The design of large parts of an airframe is driven by post buckling stability requirements. The aim of the present work is to compare stability predictions obtained both by analytical and numerical methods. A study on the sensitivity of this method to material law has also been conducted. This way, the extent to which the precise shape of an high performance aluminium alloy stress / strain curve has an impact on stability results has been evaluated. Compression studies lead to acceptable differences between methods. The trend is however depending on the model : numeric al calculations predict lower critical loads as well as upper ones. The field of improvement is undoubtedly modelling methods such as the introduction of a perturbation in the mesh and boundary conditions. More work is needed to better understand these differences. The study of the influence of the material also shows differences between both methods. Little changes are found when using detailed material model with an...
43rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2002
The design of large parts of the airframe is driven by compression stability requirements. This s... more The design of large parts of the airframe is driven by compression stability requirements. This stability is generally evaluated using a Ramberg-Osgood (R-O) model of the material. The objective of the present work is to evaluate to what extent the precise shape of the stress-strain curve determines the outcome of the stability analysis. R-O-based material models with nc fitted for various ranges of plastic strain were compared to data measured both in the micro-plastic strain domain (between 0 and 0.2% strain) and conventional stress-strain data (measured between roughly 0.2 and 8%) for an AA7xxx alloy. It was observed that R-O-based models are not capable of representing all of the measured data accurately: models fitted for larger ranges of strain (e.g. 0.2 – 1%) represented the stress-strain data measured in the micro-plastic domain poorly, and vice-versa. It was verified however, that when using the material models to compute critical stresses of post-buckling designs through analytical-empirical Euler-Engesser calculations, little improvement in precision over current generally accepted practice is possible. On the other hand, detailed comparisons of post-buckling stiffened panel stability with finite element analyses (FEA) did demonstrate room for improvement of the accuracy of the analysis by using a different stress-strain fit. This was concluded to be attributable to a more accurate representation of local phenomena: The analytical-empirical methods used model the buckling of the stiffener + effective plating as if it were the collapse of an idealized column. Strains are averaged over the entire section and therefore remain small. The buckling stress is determined by the tangent modulus at this small plastic strain. The higher the strain hardening as modeled in the R-O representation, the higher the tangent modulus for small strains and therefore the higher the predicted critical stress. Elastic-plastic geometrically non-linear FEA, on the contrary, is not limited to simulating a column. All deformations, however local, are taken into account. Also, manufacturing imperfections can be simulated. For the panel configuration and perturbation practice used for these studies, the simulations lead to locally high plastic strains. Trend analysis indicated that without the correct material models, different from the ones that are used conventionally, this may lead to non-negligible imprecision in the predicted performance of a stiffened panel when using FEA.
Volume 2: 28th Design Automation Conference, 2002
Designing a family of product variants that share some components usually entails a performance l... more Designing a family of product variants that share some components usually entails a performance loss relative to the individually optimized variants due to the commonality constraints. Choosing components for sharing may depend on what performance losses can be tolerated. This article presents a methodology for making commonality decisions while controlling individual performance losses. Previous work focused on evaluating individual performance losses due to pre-specified sharing. Trade-offs were identified for different platforms (i.e., the sets of components shared among products) by means of Pareto sets. In the present work an optimal design problem is formulated to choose product components to be shared without exceeding a user-specified performance loss tolerance. This enables the designer to control trade-offs and obtain optimal product family designs for different levels of performance losses in an attempt to maximize commonality. A family of automotive side frames is used t...
Structural and Multidisciplinary Optimization, 2004
Journal of Mechanical Design, 2005
Designing a family of product variants that share some components usually requires a compromise i... more Designing a family of product variants that share some components usually requires a compromise in performance relative to the individually optimized variants due to the commonality constraints. Choosing components for sharing may depend on what performance losses can be tolerated. In this article an optimal design problem is formulated to choose product components to be shared without exceeding user-specified bounds on performance. This enables the designer to control tradeoffs and obtain optimal product family designs for maximizing commonality at different levels of acceptable performance. A family of automotive body side frames is used to demonstrate the approach.
Archivos De Criminologia Criminalistica Y Seguridad Privada, 2012