2,439 research outputs found
Emmanuel Kutik
No full textabstract: Emmanuel Kutik was almost eight years old when he left his home. He walked for three months and traveled with fifty people.
“Lost Boys Found” is an ongoing, interdisciplinary project that is collecting, recording and archiving the oral histories of the Lost Boys/Girls of Sudan. The collection is a work-in-progress, seeking to record the oral history of as many Lost Boys/Girls as are willing, and will be used in a future book.Age: 23Region: BentiuThis picture and bio was donated to the Lost Boys Found project from The Arizona Lost Boys Cente
Yaw-modelling using a skewed vortex cylinder
No full textThe cylindrical vortex wake model presented in Chap. 17 for the case of uniform inflow is extended in the current chapter to the case of yawed inflow. Generalities regarding yaw are presented in Sect. 6.1 and only the skewed cylindrical vortex model is presented in this chapter. The chapter starts with a literature review on the topic of yaw-models and vorticity-based methods. The description of the model follows. The novelty of the current model is that the assumption of infinite tip-speed ratio is relaxed. The bound vorticity is assumed to be identical to the case of uniform inflow but the vortex cylinder and the root vortex are skewed with respect to the normal of the rotor disk. Closed form formulae for the induced velocities are provided. They can only be evaluated analytically for a limited part of the domain. A numerical integration is required to obtain the velocity everywhere in the domain. The numerical integration poses no difficulty for modern computers. Semi-empirical models are established to obtain the velocity at the rotor disk. The contribution from each vorticity components to the induced velocity at the rotor disk is investigated. The content of this chapter is based on the publication of the author titled “Cylindrical vortex wake model: skewed cylinder, application to yawed or tilted rotors� (Branlard, Gaunaa, Wind Energy, 2015, [1]). Details on the mathematical derivations used in this chapter are provided in Chap. 38. Results from this chapter are applied in Chap. 22 to derive a new yaw-model applicable to a BEM code. The induction zone in front of a yawed wind turbine or rotor is investigated in Chap. 24 based on the results from the current chapter. A Matlab source code to evaluate the induced velocity field in the entire domain due to the main vorticity component is provided in Sect. 38.1.4
Aeroelastic simulation of a wind turbine under turbulent and sheared conditions
No full textThe simulation of turbulence introduced in Chap. 29 is extended in this chapter by adding a sheared inflow, also modelled using vortex particles. The chapter starts by discussing the representation of shear in vortex methods. The notions of frozen shear and unfrozen shear are introduced and the vorticity equations are developed for these situations. It is shown that vortex methods tend to omit a term witch is non-negligible when sheared-inflow simulations are performed. The methods perform frozen shear simulation in an erroneous way, which implies that the turbine wake is deflected upward. The numerical implementation of unfrozen shear is discussed and a solution referred to as a Neumann-to-Dirichlet map (or external map) is used to account for the infinite support of the vorticity and the finite computational domain. The method is then applied for full-blown aeroelastic simulations of a wind turbine with shear and turbulence. The possibility to perform aeroelastic simulations of wind turbine under sheared and turbulent conditions using vortex methods is demonstrated. The modelling of turbulence is described in Chap. 29. The elasticity is handled by performing a coupling of the aerodynamic vortex code with the aero-servo-elastic solver HAWC2. The large eddy simulations (LES) performed with the vortex code confirms that the wake should not follow an upward motion when the shear is unfrozen. Results from this chapter are published in the article titled “Aeroelastic large eddy simulations using vortex methods: unfrozen turbulent and sheared inflow” (Branlard et al., J. Phys. Conf. Ser. 625, 2015, [2])
Honorable Emmanuel Okocha Oral History Interview
No full textThis is an oral history interview with the Honorable Emmanuel Okocha, author of Blood on the Niger, the only book about the Asaba Massacre, a mass killing of civilians which occurred in 1967 during the Nigerian Civil War. Okocha, a survivor of the massacre, was a small child at the time; his father was killed at Asaba, and two older brothers also died during the war. Okocha began researching the massacre after finishing his university studies, and has interviewed hundreds of survivors and relatives of those who were killed. He describes some of his research, the publication of his book, and his efforts to document the massacre
Emmanuel Cooper OBE 1938–2012 A Retrospective Exhibition
No full textDr Emmanuel Cooper OBE (HonDFA) 1938–2012 was a distinguished craftsman, writer, teacher and broadcaster. A potter of international standing, his work is represented in many public collections. The author of nearly thirty books, he was editor of Ceramic Review, visiting Professor at London’s Royal College of Art, and a regular broadcaster on television and radio. He was awarded an OBE in 2002 for services to art. Emmanuel’s contribution to the world of ceramics was hugely significant. This will be celebrated with a touring exhibition of his ceramics and a publication looking at his life in pots – produced by Ruthin Craft Centre in collaboration with the University of Derby
Immobile History: An Interview with Emmanuel Le Roy Ladurie
No full textThe author spoke with renowned French historian Emmanuel Le Roy Ladurie about Computers, Geography and History. Le Roy Ladurie was the "standard bearer" of the third generation of the French Annales school, a group of French intellectuals that combined different disciplines such as history, geography, anthropology, and more to delve into social history
Symbolic Flexible Multibody Models for Wind Turbine Controller Design and Analysis
No full textThe next generation of wind turbine digital technologies requires versatile aero-servo-hydro-elastic models of various levels of fidelity, and suitable for a wide range of applications. Currently, such models are usually one-off developments for a specific purpose, that are often based on a heuristic structure and only keep a lose connection to the underlying physics. Even small changes often require an extensive redevelopment or re-identifiction and many model parts and parameters can not be reused (Simani, 2015).
To address this issue, we propose a framework for the automatic derivation, processing and parametrization of models with a varying degree of detail. Our approach is based on Kane’s method (Kane and Wang, 1965) and a nonlinear modal representation of flexible bodies that are described using a standard input format (Wallrapp, 1994), (Schwertassek and Wallrapp, 1999). The method yields compact symbolic equations of motion with implicit account of the constraints. The parameters needed for these models are the same as those for high-fidelity simulators such as OpenFAST. A parameter identification from time-series data is not required (La Cavae et al., 2016), (Loew and Obradovic, 2018).
In this work, we use well-establish techniques and leverage the current capabilities of symbolic calculation packages to allow users to easily generate models suitable for their applications, such as:
Linearization, for controller design and tuning, or for frequency domain analysis
Derivation of exact gradients for optimization procedures
Automatic generation of dedicated code for applications such as: Simulink models, standalone simulators, state observers, or digital twins
Further processing by specialized tools, e.g. for the generation of high performance NMPC code such as acados (Verschueren et al., 2018)
Contrary to the approach of Merz (2018), our framework processes all equations on a symbolic level and thus, the model can be used in its nonlinear or linearized form. Our approach is severalfold faster than multiple OpenFAST linearizations because it gives results for all operating points at once.
Most importantly, the different applications listed above are obtained from the same standardized and intuitive model description. The user only needs to describe the individual bodies of the system, their connections, the forces acting on them, and chose a set of generalized coordinates to describe the motion (Branlard, 2019). This makes it very easy to quickly vary the level of detail, e.g. choosing stiff or flexible blades, or the number of modes, or even the same coordinate for all three blades to yield a model with collective-only blade motion. Composing a model in this way makes it possible to tailor the level of detail in a modular fashion (Shabana, 2013).
In the presentation, we will describe the method used in our framework, and illustrate how the equations of motion are generated. We will compare our results with OpenFAST simulations for different models, we will present how we currently use this framework, and how it can be applied to various research projects.
Our framework is currently developed in two variations:
https://github.com/jgeisler0303/CADynTurb (based on Maxima and MATLAB) and
https://github.com/ebranlard/welib (based on python).
References:
Branlard, E. S. P. (2019). Flexible multibody dynamics using joint coordinates and the Rayleigh-Ritz approximation: The general framework behind and beyond Flex. Wind Energy, 22 (7), https://doi.org/10.1002/we.2327
Kane, T. R., & Wang, C. F. (1965). On the Derivation of Equations of Motion. Journal of the Society for Industrial and Applied Mathematics, 13 (2), 487-492. https://doi.org/https://doi.org/10.1137/0113030
Kurz, T., & Eberhard, P. (2009). Symbolic Modeling and Analysis of Elastic Multibody Systems, In Proceedings of the International Symposium on Coupled Methods in Numerical Dynamics, Split, Croatia.
La Cava, W., Danai, K., Spector, L., Fleming, P., Wright, A., & Lackner, M. (2016). Automatic identification of wind turbine models using evolutionary multiobjective optimization. Renewable Energy, 87, 892-902.
Loew, S., & Obradovic, D. (2018). Real-time Implementation of Nonlinear Model Predictive Control for Mechatronic Systems Using a Hybrid Model, In 2018 IEEE 14th International Conference on Automation Science and Engineering (CASE). https://doi.org/10.1109/COASE.2018.8560359
Merz, K. O. (2018). STAS Aeroelastic 1.0 - Theory Manual. Trondheim, SINTEF Energi AS.
Schwertassek, R., & Wallrapp, O. (1999). Dynamik Flexibler Mehrkörpersysteme. Braunschweig, Friedr. Vieweg & Sohn.
Shabana, A. (2013). Dynamics of Multibody Systems, Dynamics of Multibody Systems. Cambridge University Press.
Simani, S. (2015). Advanced Issues of Wind Turbine Modelling and Control. Journal of Physics: Conference Series, 659, 012001. https://doi.org/10.1088/1742-6596/659/1/012001
Verschueren, R., Frison, G., Kouzoupis, D., van Duijkeren, N., Zanelli, A., Quirynen, R., & Diehl, M. (2018). Towards a modular software package for embedded optimization [6th IFAC Conference on Nonlinear Model Predictive Control NMPC 2018]. IFAC-PapersOnLine, 51 (20), 374-380. https://doi.org/10.1016/j.ifacol.2018.11.062
Wallrapp, O. (1994). Standardization of Flexible body modeling in multibody system codes, Part I: Definition of standard input data. Journal of Structural Mechanics, 22 (3), 283-304
Emmanuel B. Dongala
No full textA chapter on Congolese writer Emmanuel B. Dongala in the Dictionary of Literary Biography. (Vol. 360: Contemporary Arican Writers). --author-supplied descriptio
Can reforming global institutions help developing countries share more in the benefits from globalization?
No full textGlobalization could significantly expand trade, international investment, and technological advances, but the gains from global integration have been unevenly distributed across and within nations. Greater global interdependence has also brought greater macroeconomic volatility, resulting in several serious financial crises in the second half of the 1990s. The global matrix of Bretton Woods and United Nations institutions that developed starting in the 1940s, formed under a different balance of power, in a world of fixed exchange rates and limited capital mobility. Since the 1960s regional financial institutions have emerged because of the greater autonomy of different regions and the greater financial needs of development. The author reviews different proposals for reform of the international financial institutions and changes in the roles of the International Monetary Fund (IMF) and the World Bank. He highlights the implications for developing countries of (1) Policy conditionality. (2) The countercyclical role of multilaterals'lending. (3) Greater lending to middle-income than to low-income developing countries. (3) Access to liquidity at times of crisis. (4) Mechanisms for giving low-income countries a greater voice in IMF and World Bank decisionmaking. The author streses the overlapping responsibilities of the Bretton Woods and regional financial institutions and the need to reassess the allocation of responsibilities and to develop better coordination mechanisms between these institutions. Those designing institutional reform must consider the corporate capabilities of each type of institution. The corporate cultures of global and regional institutions differ. So does the kind of knowledge they generate and disseminate, and so do patterns of interactions with, and mechanisms for representation of, client countries.Finally, the author calls attention to the need to harmonize national and global growth-oriented policies in a way that reduces volatility and promotes social equity.Environmental Economics&Policies,Governance Indicators,Financial Intermediation,Economic Theory&Research,Banks&Banking Reform
A formação de professores em e para direitos humanos na perspectiva filosófica de Emmanuel Levinas
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Educação, Programa de Pós-Graduação em Educação, Florianópolis, 2013.O presente trabalho tem como proposta refletir a formação de professores em e para direitos humanos na perspectiva filosófica de Emmanuel Levinas. Este autor propõe a ética como filosofia primeira, uma vez que a concebe como resposta à interpelação do Outro. Ela seria um caminho para resistir à ontologização e, consequentemente, à totalização. A ética levinasiana origina-se no reconhecimento da alteridade do Outro, sendo o rosto a manifestação da singularidade de cada pessoa, motivo pelo qual todo ser humano é possuidor de dignidade, um dos fundamentos dos direitos humanos. A relação ética Eu-Outro, bem como com terceiros (estrangeiro) é assimétrica, pois, desestabiliza e exige dos sujeitos dialogantes abertura, acolhimento e responsabilidade, emergindo daí a necessidade de pensar uma política na perspectiva da outridade. Portanto, uma proposta formativa pensada e articulada a partir do reconhecimento da alteridade faz irromper o inesperado, o imprevisível da vida que viria questionar concepções e práticas formativas que subordinam e colonizam o Outro, reduzindo-o ao Mesmo. Neste sentido, ainda que se reconheça a complexidade quanto à fundamentação filosófica dos direitos humanos, é intransferível a responsabilidade de pensar a formação de professores em uma perspectiva de uma pedagogia da alteridade, justificando-se assim a relevância da abordagem a qual nos propomos. Por isso, uma formação em e para direitos humanos na perspectiva filosófica de Levinas tem de ter seu fundamento na interpelação ética do Outro, cujos encaminhamentos curriculares e metodológicos se constituem em respostas aos seus apelos. Esta formação não possui encerramento em uma cerimônia de colação de grau, pois se caracteriza como inacabamento, incompletude e constante abertura à novidade que se manifesta no rosto do Outro, exigindo outros tempos, espaços, currículos e metodologias para processos formativos emancipadores. Este trabalho é de cunho qualitativo e está organizado em cinco momentos: no primeiro apresentamos o contexto e a introdução à temática da formação e dos direitos humanos; no segundo momento, tratamos da complexidade que entorna o conceito de direitos humanos; no terceiro, abordamos o pensamento levinasiano, especialmente as categorias alteridade, responsabilidade e interpelação ética; no quarto momento, refletimos os desafios e possibilidades de pensar a formação de professores na perspectiva da ética e pedagogia da alteridade e; finalizamos com algumas considerações que percebemos como necessárias, reconhecendo várias aberturas para possibilidades futuras de pesquisas, estudos e reflexões. Abstract : This present work aims to reflect the teachers education in and for human rights in the philosophical perspective of Emmanuel Levinas. This author proposes ethics as first philosophy, once conceives it as a response to the interpellation of the Other. It would be a way to resist to the ontologization and hence aggregation. Levinasian ethics originates in the recognition of the otherness of the Other, being the face, the manifestation of the uniqueness of each person, which is because every human being is possessed of dignity, one of the foundations of human rights. The ethical relation me - Other, and with third parties (foreign) is asymmetric because destabilizes and requires from the subjects dialoguers openness, acceptance and responsibility, emerging hence the need for a policy thinking from the perspective of othernes. Therefore, a training proposal conceived and articulated from the recognition of otherness does erupt the unexpected , the unpredictable of life and it would come to question concepts and training practices that subordinate and colonize the Other , reducing him to the Same . In this sense, although it recognizes the complexity as the philosophical foundation of human rights, is non-transferable responsibility of thinking about teacher education in a perspective of alterity pedagogy, thus justifying the relevance of the approach which we propose. Therefore, training in and for human rights in Levinas philosophical perspective, must have its foundation in ethical interpellation of the Other, whose curricular and methodological referrals constitute responses to their requests. This training does not have closure in a graduation ceremony, because it characterizes itself as unfinished, incompleteness and constant opening to novelty manifested on the face of the Other, requiring other times, spaces, curricula and methodology for emancipatory educational processes. This work is a qualitative one and it is organized into five parts: the first presents the context and introduction to the theme of education and human rights, in the second moment, we deal with the complexity that spills the concept of human rights, on the third, approach the Levinasian thought, especially the categories otherness, responsibility and ethical interpellation, in the fourth part, we reflect on the challenges and possibilities of thinking about teacher education from the ethics perspective and otherness pedagogy and finalizing with some considerations that we have perceived as necessary, recognizing several openings for future research possibilities studies and reflections
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