167 research outputs found

    2013-2014, University of Memphis bulletin

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    University of Memphis bulletin containing the graduate catalog for 2013-2014.https://digitalcommons.memphis.edu/speccoll-ua-pub-bulletins/1434/thumbnail.jp

    2009-2010, University of Memphis bulletin

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    University of Memphis bulletin containing the graduate catalog for 2009-2010.https://digitalcommons.memphis.edu/speccoll-ua-pub-bulletins/1429/thumbnail.jp

    2014-2015, University of Memphis bulletin

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    University of Memphis bulletin containing the graduate catalog for 2014-2015.https://digitalcommons.memphis.edu/speccoll-ua-pub-bulletins/1433/thumbnail.jp

    2011-2012, University of Memphis bulletin

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    University of Memphis bulletin containing the graduate catalog for 2011-2012.https://digitalcommons.memphis.edu/speccoll-ua-pub-bulletins/1431/thumbnail.jp

    A new mixed model based on the enhanced-Refined Zigzag Theory for the analysis of thick multilayered composite plates

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    The Refined Zigzag Theory (RZT) has been widely used in the numerical analysis of multilayered and sandwich plates in the last decay. It has been demonstrated its high accuracy in predicting global quantities, such as maximum displacement, frequencies and buckling loads, and local quantities such as through-the-thickness distribution of displacements and in-plane stresses [1,2]. Moreover, the C0 continuity conditions make this theory appealing to finite element formulations [3]. The standard RZT, due to the derivation of the zigzag functions, cannot be used to investigate the structural behaviour of angle-ply laminated plates. This drawback has been recently solved by introducing a new set of generalized zigzag functions that allow the coupling effect between the local contribution of the zigzag displacements [4]. The newly developed theory has been named enhanced Refined Zigzag Theory (en- RZT) and has been demonstrated to be very accurate in the prediction of displacements, frequencies, buckling loads and stresses. The predictive capabilities of standard RZT for transverse shear stress distributions can be improved using the Reissner’s Mixed Variational Theorem (RMVT). In the mixed RZT, named RZT(m) [5], the assumed transverse shear stresses are derived from the integration of local three-dimensional equilibrium equations. Following the variational statement described by Auricchio and Sacco [6], the purpose of this work is to implement a mixed variational formulation for the en-RZT, in order to improve the accuracy of the predicted transverse stress distributions. The assumed kinematic field is cubic for the in-plane displacements and parabolic for the transverse one. Using an appropriate procedure enforcing the transverse shear stresses null on both the top and bottom surface, a new set of enhanced piecewise cubic zigzag functions are obtained. The transverse normal stress is assumed as a smeared cubic function along the laminate thickness. The assumed transverse shear stresses profile is derived from the integration of local three-dimensional equilibrium equations. The variational functional is the sum of three contributions: (1) one related to the membrane-bending deformation with a full displacement formulation, (2) the Hellinger-Reissner functional for the transverse normal and shear terms and (3) a penalty functional adopted to enforce the compatibility between the strains coming from the displacement field and new “strain” independent variables. The entire formulation is developed and the governing equations are derived for cases with existing analytical solutions. Finally, to assess the proposed model’s predictive capabilities, results are compared with an exact three-dimensional solution, when available, or high-fidelity finite elements 3D models. References: [1] Tessler A, Di Sciuva M, Gherlone M. Refined Zigzag Theory for Laminated Composite and Sandwich Plates. NASA/TP- 2009-215561 2009:1–53. [2] Iurlaro L, Gherlone M, Di Sciuva M, Tessler A. Assessment of the Refined Zigzag Theory for bending, vibration, and buckling of sandwich plates: a comparative study of different theories. Composite Structures 2013;106:777–92. https://doi.org/10.1016/j.compstruct.2013.07.019. [3] Di Sciuva M, Gherlone M, Iurlaro L, Tessler A. A class of higher-order C0 composite and sandwich beam elements based on the Refined Zigzag Theory. Composite Structures 2015;132:784–803. https://doi.org/10.1016/j.compstruct.2015.06.071. [4] Sorrenti M, Di Sciuva M. An enhancement of the warping shear functions of Refined Zigzag Theory. Journal of Applied Mechanics 2021;88:7. https://doi.org/10.1115/1.4050908. [5] Iurlaro L, Gherlone M, Di Sciuva M, Tessler A. A Multi-scale Refined Zigzag Theory for Multilayered Composite and Sandwich Plates with Improved Transverse Shear Stresses, Ibiza, Spain: 2013. [6] Auricchio F, Sacco E. Refined First-Order Shear Deformation Theory Models for Composite Laminates. J Appl Mech 2003;70:381–90. https://doi.org/10.1115/1.1572901

    Tools and Algorithms for the Construction and Analysis of Systems

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    This open access book constitutes the proceedings of the 28th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2022, which was held during April 2-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 46 full papers and 4 short papers presented in this volume were carefully reviewed and selected from 159 submissions. The proceedings also contain 16 tool papers of the affiliated competition SV-Comp and 1 paper consisting of the competition report. TACAS is a forum for researchers, developers, and users interested in rigorously based tools and algorithms for the construction and analysis of systems. The conference aims to bridge the gaps between different communities with this common interest and to support them in their quest to improve the utility, reliability, exibility, and efficiency of tools and algorithms for building computer-controlled systems

    Identifying the Neurocognitive bases of creativity to increase human and computational creativity

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    En esta Tesis Doctoral se ha identificado la estructura neurocognitiva que sustenta la creatividad humana a partir del análisis conjunto de más de 800 referencias bibliográficas que muestran las investigaciones más importantes realizadas hasta la fecha. Sobre la base de esta estructura, se ha identificado un paradigma neurocognitivo de la creatividad humana y se ha propuesto un modelo neurocognitivo del proceso creativo. Finalmente, también se ha propuesto un paradigma creativo neurocognitivo computacional y se ha diseñado la estructura de un sistema computacional creativo, basado en una estructura multiagente. La investigación que se ha realizado sobre el tema hasta la fecha es muy especializada y se centra en aspectos muy concretos de la creatividad, y en muchos casos tienen poca relación entre sí. Por ello, y para tener una idea conjunta y holística de los procesos neurocognitivos de la creatividad humana, es necesario estudiar todas estas investigaciones de forma interconectada. Esta idea conjunta permitiría dirigir investigaciones más específicas para ser más efectivos. Por ello, lo primero que se ha hecho ha sido clasificar, agrupar, analizar, entrelazar y estructurar, de forma ordenada, las investigaciones más importantes que se han realizado hasta la fecha. Sin embargo, el trabajo realizado va mucho más allá, ya que estructurando y entrelazando las investigaciones existentes ha sido posible identificar ciertos patrones, correlaciones y paralelismos, y realizar ciertas deducciones, que en su conjunto, han permitido identificar los procesos neurocognitivos fundamentales. bases de la creatividad humana. La Tesis se estructura en los siguientes capítulos: Capitulo 2 Análisis de los principales métodos para estimular la creatividad Se analizan las principales definiciones de creatividad, y se ha decidido que el mejor enfoque para su análisis es estructurarla taxonómicamente, bajo el modelo 4P. Se ha realizado una recopilación y análisis de los métodos más efectivos que estimulan la creatividad humana, mostrando las ventajas y desventajas de cada uno. Capítulo 3 Estructura funcional del cerebro humano y su relación con el proceso creativo Se identifica la estructura neurocognitiva general del cerebro humano que permite generar los procesos fundamentales y básicos de su actividad creativa. Capítulo 4 El papel fundamental de la DMN en el proceso creativo Se ha observado que la red de modo predeterminado (DMN) tiene un papel principal en la creatividad. Por ello, se ha dedicado un capítulo a su estudio, y se han identificado varios factores que la involucran directamente en la actividad creativa del cerebro humano. Capítulo 5 Identificación y análisis de las bases neurocognitivas de la creatividad humana Se ha identificado el conjunto general de factores neurocognitivos que sustentan los procesos creativos en el cerebro humano. Capítulo 6 Paradigma neurocognitivo de la creatividad humana Se ha propuesto un modelo neurocognitivo del proceso creativo que reestructura, completa y detalla todos los modelos conceptuales propuestos hasta el momento. Capítulo 7 Paradigma computacional de la creatividad basado en la estructura neurocognitiva humana Analizando las diferentes bases neurocognitivas que sustentan la creatividad humana, se han establecido paralelismos computacionales y se han realizado diferentes sugerencias para el diseño de un sistema computacional creativo.In this Doctoral Thesis, the neurocognitive structure that supports human creativity has been identified based on the joint analysis of more than 800 bibliographical references that show the most important investigations carried out to date. Based on this structure, a neurocognitive paradigm of human creativity has been described, and a neurocognitive model of creative process has been proposed. Finally, a computational neurocognitive creative paradigm has been also proposed, and the structure of a creative computational multi-agent system has been designed. The research that has been carried out on the subject is very specialized and focuses on very specific aspects of creativity, and in many cases they have little relationship with each other. For this reason, and in order to have a joint and holistic idea of the neurocognitive processes of human creativity, it is necessary to study all these investigations in an interconnected way. This joint idea would allow directing more specific investigations in order to be more effective. For this reason, the first thing that has been done has been to classify, group, analyze, intertwine and structure, in an orderly manner, the most important investigations that have been carried out to date. However, the work carried out goes much further, since by structuring and intertwining the existing research it has been possible to identify certain patterns, correlations and parallelisms, and make certain deductions, which as a whole, have made it possible to identify the fundamental neurocognitive bases of human creativity. Chapter 2 Analysis of the main methods to stimulate creativity The main definitions of creativity are analyzed, and it has been decided that the best approach for its analysis is to structure it taxonomically, under the 4P model. A compilation and analysis of the most effective methods that stimulate human creativity has been carried out, showing the advantages and disadvantages of each one. Chapter 3 Functional structure of the human brain and its relationship with the creative process The general neurocognitive structure of the human brain that allows the generation of the fundamental and basic processes of its creative activity are identified. Chapter 4 The fundamental role of the DMN in the creative process It has been observed that the Default mode network (DMN) has a main role in creativity. For this reason, a chapter has been dedicated to its study, and several factors have been identified that directly involve it in the creative activity of the human brain. Chapter 5 Identification and analysis of the neurocognitive bases of human creativity The general set of neurocognitive factors that underpin creative processes in the human brain has been identified. Chapter 6 Neurocognitive paradigm of human creativity A neurocognitive model of the creative process has been proposed, which restructures, completes and details all the conceptual models proposed so far. Chapter 7 Computational paradigm of creativity based on the human neurocognitive structure Analyzing the different neurocognitive bases that support human creativity, computational parallels have been established and different suggestions have been made for the design of a creative computational system
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